I 


1 

I 


Soap-Making  Manual 

A   practical  handbook   on   the   raw 
materials,  their  manipulation,  anal- 
ysis   and    control    in    the    modern 
soap  plant. 


By 
E.  G.  Thomssen,  Ph.  D. 


ILLUSTRATED 


NEW    YORK 

D.    VAN   NOSTRAND   COMPANY 

EIGHT  WARREN  STREET 

1922 


COPYRIGHT  1922 

BY 
D.  VAN  NOSTRAND  COMPANY 


Printed  in  the  United  States  of  America 


PREFATORY    NOTE. 

The  material  contained  in  this  work  appeared  sev- 
eral years  ago  in  serial  form  in  the  American  Perfumer 
and  Essential  Oil  Review.  Owing  to  the  numerous  re- 
quests received,  it  has  been  decided  to  now  place  before 
those  interested,  these  articles  in  book  form.  While  it 
is  true  that  the  works  pertaining  to  the  soapmaking 
industry  are  reasonably  plentiful,  books  are  quite  rare, 
however,  which,  in  a  brief  volume,  will  clearly  outline 
the  processes  employed  together  with  the  neces- 
sary methods  of  analyses  from  a  purely  practical 
standpoint.  In  the  work  presented  the  author  has 
attempted  to  briefly,  clearly,  and  fully  explain  the 
manufacture  of  soap  in  such  language  that  it  might  be 
understood  by  all  those  interested  in  this  industry.  In 
many  cases  the  smaller  plants  find  it  necessary  to  dis- 
pense with  the  services  of  a  chemist,  so  that  it  is  neces- 
sary for  the  soapmaker  to  make  his  own  tests.  The 
tests  outlined,  therefore,  are  given  as  simple  as  possi- 
ble to  meet  this  condition.  The  formulae  submitted 
are  authentic,  and  in  many  cases  are  now  being  used 
in  soapmaking. 

In  taking  up  the  industry  for  survey  it  has  been  thought 
desirable  to  first  mention  and  describe  the  raw  materials 
used;  second,  to  outline  the  processes  of  manu- 
facture; third,  to  classify  the  methods  and  illustrate 
by  formulae  the  composition  of  various  soaps  together 
with  their  mode  of  manufacture ;  fourth,  to  enumerate  the 
various  methods  of  glycerine  recovery,  including  the 
processes  of  saponification,  and,  fifth,  to  give  the  most  im- 
portant analytical  methods  which  are  of  value  to  control 
in 


the  process  of  manufacture  and  to  determine  the  purity 
and  fitness  of  the  raw  material  entering  into  it. 

It  is  not  the  intention  of  the  author  to  go  into  great 
detail  in  this  work,  nor  to  outline  to  any  great  extent  the 
theoretical  side  of  the  subject,  but  rather  to  make  the  work 
as  brief  as  possible,  keeping  the  practical  side  of  the  sub- 
ject before  him  and  not  going  into  concise  descriptions  of 
machinery  as  is  very  usual  in  works  on  this  subject. 
Illustrations  are  merely  added  to  show  typical  kinds 
of  machinery  used. 

The  author  wishes  to  take  this  opportunity  of  thank- 
ing Messrs.  L.  S.  Levy  and  E.  W.  Drew  for  the  reading 
of  proof,  and  Mr.  C.  W.  Aiken  of  the  Houchin-Aiken  Co., 
for  his  aid  in  making  the  illustrations  a  success,  as 
well  as  others  who  have  contributed  in  the  compil- 
ing of  the  formulae  for  various  soaps.  He  trusts  that 
this  work  may  prove  of  value  to  those  engaged  in  soap 
manufacture. 

E.  G.  T. 
January,    1922 


IV 


TABLE    OF    CONTENTS, 

CHAPTER    I.  Page. 

RAW  MATERIALS  USED  IN  SOAP  MAKING 1-  30 

1.  Soap    Defined    , ;.  1 

2.  Oils  and  Fats 1-     2 

3.  Saponification    Defined    2-     3 

4.  Fats  and  Oils  Used  in  Soap  Manufacture 3-     4 

Fullers'  Earth  Process  for  Bleaching  Tallow 4-     6 

Method  for  Further  Improvement  of  Color  in  Tallow  6 

Vegetable   Oils 6-     9 

Chrome  Bleaching  of  Palm  Oil 9-  12 

Air  Bleaching  of  Palm  Oil 12-  16 

5.  Rancidity  of  Oils  and  Fats 16-  18 

Prevention    of   Rancidity 18 

6.  Chemical  Constants  of  Oils  and  Fats 18-  19 

7.  Oil  Hardening  or  Hydrogenating 19-  21 

8.  Grease    21-  22 

9.  Rosin  (Colophony,  Yellow  Rosin,  Resina) 22-  23 

10.  Rosin   Saponification 23-  24 

11.  Naphthenic  Acids  24-  25 

12.  Alkalis 25-  26 

Caustic  Soda   26 

Caustic   Potash    26-  28 

Sodium  Carbonate   (Soda  Ash) 28-  29 

Potassium    Carbonate    29 

13.  Additional  Material  Used  in  Soap  Making 29-  30 

CHAPTER  II. 

CONSTRUCTION  AND  EQUIPMENT  OF  A  SOAP  PLANT 31-  34 

CHAPTER   III 

CLASSIFICATION  OF  SOAP  MAKING  METHODS • 35-46 

1.  Full   Boiled   Soaps 36-  42 

2.  Cold  Process    43-  44 

3.  Carbonate   Saponification    45-  46 

CHAPTER  IV. 

CLASSIFICATION    OF    SOAPS 47-104 

1.  Laundry  Soap 48 

Semi-Boiled  Laundry  Scap 49-  50 

Settled  Rosin  Soap 50-  54 

2.  Chip  Soap    54-55 

V 


SOAP-MAKING    MANUAL 

Page. 

Cold  Made  Chip  Soap 55-  56 

Unfilled  Chip  Soap 56 

J.  Soap   Powders    , 56-  59 

Li?ht  Powders    60-  61 

4.  Scouring    Powders     61 

5.  Scouring   Soap    61-  62 

6.  Floating    Soap    62-  65 

7.  Toilet  Soap   65-  68 

Cheaper  Toilet  Soaps 68-  69 

Run  and  Glued-up  Soaps 69-  71 

Curd  Soap   71-  72 

Cold  Made  Toilet  Soaps 72-  73 

Perfuming  and  Coloring  Toilet  Soaps 73-  75 

Coloring    Soap    75-  76 

8.  Medicinal  Soaps   76-  77 

Sulphur   Soaps    77 

Tar  Soap 77 

Soaps    Containing    Phenols 77-  78 

Peroxide   Soap    78 

Mercury  Soaps   78 

Less  Important  Medicinal  Soaps 78-  79 

9.  Castile  Soap   79-  81 

10.  Eschweger  Soap   81-  82 

11.  Transparent  Soap   82-  84 

Cold  Made  Transparent  Soap 84-87 

12.  Shaving  Soaps   87-  90 

Shaving  Powder  90 

Shaving  Cream   90-  93 

12.  Pumice  or  Sand  Soaps 93-  94 

14.  Liquid  Soaps  94-  95 

15.  Use  of  Hardened  Oils  in  Toilet  Soaps 96-  98 

16.  Textile   Soaps    98 

Scouring  and  Fulling  Soaps  for  Wool 98-100 

Wool  Thrower's  Soap 100-101 

Worsted  Finishing  Soaps 101 

Soaps  Used  in  the  Silk  Industry 101-103 

Soaps  Used  for  Cotton  Goods 103-104 

17.  Sulphonated    Oils     104-105 

CHAPTER  V. 

GLYCERINE  RECOVERY 105-126 

1.  Methods  of  Saponification 105-106 

VI 


TABLE  OF   CONTENTS 

Page. 

Recovery  of  Glycerine  from  Spent  Lye 106-113 

Twitckell  Process 113-118 

Autoclave   Saponification    118 

Lime  Saponification   1 18-120 

Acid  Saponification   120-121 

Aqueous  Saponification   121 

Splitting  Fats  with  Ferments 121-123 

Ki  ebitz  Process 123-125 

2.  Distillation  of  Fatty  Acids 125-126 

CHAPTER    VI. 
ANALYTICAL  METHODS   127-164 

1 .  Analysis  of  Oils  and  Fats 128 

Free  Fatty  Acids 128-130 

Moisture    130 

Titer     130-132 

Determination  of  Unsaponifiable  Matter 132-133 

Test  for  Color  of  Soap 133-134 

Testing  of  Alkalis  U?ed  in  Soap  Making 134-137 

2.  Soap  Analysis   137-138 

Moisture   138-139 

Free  Alkali  or  Acid 139-142 

Insoluble  Matter   143 

Starch  and  Gelatine   143-144 

Total  Fatty  and  Resin  Acids 144 

Determination  of  Rosin 144-147 

Total  Alkali 147-148 

Unsaponifiable  Matter 148 

Silica  and   Silicates 148-149 

Glycerine  in  Soap 149-150 

Sugar  in   Soap 150 

3.  Glycerine  Analysis    150-151 

Sampling   , 151 

Analysis    151-154 

Acetin  Process  for  the  Determination  of  Glycerol 155-156 

The  Method .156-159 

Ways  of  Calculating  Actual  Glycerol  Contents 159-160 

Bichromate    Process    for    Glycerol    Determination    Re- 
agents Required   160-161 

The  Method 161-162 

Sampling    Crude    Glycerine 162-164 

VII 


SOAP-MAKING    MANUAL 

CHAPTER  VII  Page. 

STANDARD    METHODS    FOR    THE    SAMPLING    AND    ANALYSIS    OF 

COMMERCIAL    FATS    AND    OILS 165-195 

1.  Scope,  Applicability  and  Limitations  of  the  Methods.  .  165-166 

Scope    ;  .         165 

Applicability    ' 166 

Limitations      166 

Sampling    166-169 

Tank     Cars 166-167 

Barrels,  Tierces,   Casks,   Drums,   and   Other  Packages.        168 

2.  Analysis 169-183 

Sample     169 

Moisture  and    Volatile   Matter 170-172 

Insoluble    Impurities    172-173 

Soluble   Mineral    Matter    173 

Free   Fatty  Acids    174 

Titer     174-175 

Unsaponifiable    Matter     176-177 

Iodine    Number- Wijs    Method 177-181 

Saponification  Number   (Koettstorfer  Number) 181 

Melting   Point    18.1-182 

Cloud  Test    182-184 

3.  Notes  of  the  Above  Methods 184-196 

Sampling    183 

Moisture  and  Volatile  Matter 184-187 

Insoluble  Impurities   187 

Soluble     Mineral     Matter 187-188 

Free  Fatty  Acid    188-189 

Titer     189 

Unsaponified    Matter    190-193 

Melting    Point 193-196 

Plant    and    Machinery    198-219 

Illustrations  of  Machinery  and   Layouts  of  the  Plant 

of  a   Modern   Soap   Making   Establishment 198-219 

Appendix 219-237 

Useful  Tables 

Index     ,. 239 


VIII 


CHAPTER    I 

Raw   Materials   Used  in   Soap   Making. 

Soap  is  ordinarily  thought  of  as  the  common  cleansing 
agent  well  known  to  everyone.  In  a  general  and  strictly 
chemical  sense  this  term  is  applied  to  the  salts  of  the  non- 
volatile fatty  acids.  These  salts  are  not  only  those  formed 
by  the  alkali  metals,  sodium  and  potassium,  but  also  those 
formed  by  the  heavy  metals  and  alkaline  earths.  Thus 
we  have  the  insoluble  soaps  of  lime  and  magnesia  formed 
when  we  attempt  to  wash  in  "hard  water";  again  alum- 
inum soaps  are  used  extensively  in  polishing  materials 
and  to  thicken  lubricating  oils;  ammonia  or  "benzine" 
soaps  are  employed  among  the  dry  cleaners.  Commonly, 
however,  when  we  speak  of  soap  we  limit  it  to  the  sodium 
or  potassium  salt  of  a  higher  fatty  acid. 

It  is  very  generally  known  that  soap  is  made  by  com- 
bining a  fat  or  oil  with  a  water  solution  of  sodium  hydrox- 
ide (caustic  soda  lye),  or  potassium  hydroxide  (caustic 
potash).  Sodium  soaps  are  always  harder  than  potassium 
soaps,  provided  the  same  fat  or  oil  is  used  in  both  cases. 

The  detergent  properties  of  soap  are  due  to  the  fact 
that  it  acts  as  an  alkali  regulator,  that  is,  when  water 
comes  into  contact  with  soap,  it  undergoes  what  is  called 
hydrolytic  dissociation.  This  means  that  it  is  broken 
down  by  water  into  other  substances.  Just  what  these 
substances  are  is  subject  to  controversy,  though  it  is  pre- 
sumed caustic  alkali  and  the  acid  alkali  salt  of  the  fatty 
acids  are  formed. 

OILS    AND    FATS. 

There  is  no  sharp  distinction  between  fat  and  oil.  By 
"oil"  the  layman  has  the  impression  of  a  liquid  which  at 


,t  .SO.AP-MAKING    MANUAL 

warm  temperature  'will  "flow  as  a  slippery,  lubricating,  vis- 
cous fluid;  by  "fat"  he  understands  a  greasy,  solid  sub- 
stance unctuous  to  the  touch.  It  thus  becomes  necessary 
to  differentiate  the  oils  and  fats  used  in  the  manufacture 
of  soap. 

Inasmuch  as  a  soap  is  the  alkali  salt  of  a  fatty  acid,  the 
oil  or  fat  from  which  soap  is  made  must  have  as  a  con- 
stituent part,  these  fatty  acids.  Hydrocarbon  oils  or  par- 
affines,  included  in  the  term  "oil,"  are  thus  useless  in  the 
process  of  soap-making,  as  far  as  entering  into  chemical 
combination  with  the  caustic  alkalis  is  concerned.  The 
oils  and  fats  which  form  soap  are  those  which  are  a  com- 
bination of  fatty  acids  and  glycerine,  the  glycerine  being 
obtained  as  a  by-product  to  the  soap-making  industry. 

NATURE   OF   A   FAT   OR   OIL   USED    IN    SOAP    MANUFACTURE. 

Glycerine,  being  a  tryhydric  alcohol,  has  three  atoms  of 
hydrogen  which  are  replaceable  by  three  univalent  radicals 
of  the  higher  members  of  the  fatty  acids,  e.  g., 

OH  OR 

C3  HB  OH  +  3  ROH  =  C8  H8  OR  -f-  3  H2O 

OH  OR 

Glycerine  plus  3  Fatty  Alcohols   equals  Fat  or  Oil  plus 

3  Water. 

Thus  three  fatty  acid  radicals  combine  with  one  glycer- 
ine to  form  a  true  neutral  oil  or  fat  which  are  called 
triglycerides.  The  fatty  acids  which  most  commonly  en- 
ter into  combination  of  fats  and  oils  are  lauric,  myristic, 
palmitic,  stearic  and  oleic  acids  and  form  the  neutral  oils 
or  triglycerides  derived  from  these,  e.  g.,  stearin;  palmatin, 
olein.  Mono  and  diglycerides  are  also  present  in  fats. 

SAPONIFICATION    DEFINED. 

When  a  fat  or  oil  enters  into  chemical  combination  with 
one  of  the  caustic  hydrates  in  the  presence  of  water,  the 

2 


RAW  MATERIALS 

process  is  called  "saponification"  and  the  new  compounds 
formed  are  soap  and  glycerine,  thus: 

OR  OH 

C,H6  OR  +  3  NaOH  =  QH6  OH  +  3  NaOR 

OR  OH 

Fat  or  Oil  plus  3  Sodium  Hydrate  equals  Glycerine  plus 

3  Soap. 

It  is  by  this  reaction  almost  all  of  the  soap  used  today 
is  made. 

There  are  also  other  means  of  saponification,  as,  the 
hydrolysis  of  an  oil  or  fat  by  the  action  of  hydrochloric 
or  sulfuric  acid,  by  autoclave  and  by  ferments  or  en- 
zymes. By  these  latter  processes  the  fatty  acids  and 
glycerine  are  obtained  directly,  no  soap  being  formed. 

FATS    AND    OILS    USED    IN    SOAP    MANUFACTURE. 

The  various  and  most  important  oils  and  fats  used  in 
the  manufacture  of  soap  are,  tallow,  cocoanut  oil,  palm 
oil,  olive  oil,  poppy  oil,  sesame  oil,  soya  bean  oil,  cotton- 
seed oil,  corn  oil  and  the  various  greases.  Besides  these 
the  fatty  acids,  stearic,  red  oil  (oleic  acid)  are  more  or 
less  extensively  used.  These  oils,  fats  and  fatty  acids, 
while  they  vary  from  time  to  time  and  to  some  extent  as 
to  their  color,  odor  and  consistency,  can  readily  be  distin- 
guished by  various  physical  and  chemical  constants. 

Much  can  be  learned  by  one,  who  through  continued 
acquaintance  with  these  oils  has  thoroughly  familiarized 
himself  with  the  indications  of  a  good  or  bad  oil,  by 
taste,  smell,  feel  and  appearance.  It  is,  however,  not  well 
for  the  manufacturer  in  purchasing  to  depend  entirely  upon 
these  simpler  tests.  Since  he  is  interested  in  the  yield  of 
glycerine,  the  largest  possible  yield  of  soap  per  pound  of 
soap  stock  and  the  general  body  and  appearance  of  the 
finished  product,  the  chemical  tests  upon  which  these  de- 

3 


SOAP-MAKING   MANUAL 

pend  should  be  made.  Those  especially  important  are  the 
acid  value,  percentage  unsaponifiable  matter  and  titer  test. 

A  short  description  of  the  various  oils  and  fats  men- 
tioned is  sufficient  for  their  use  in  the  soap  industry. 

Tallow  is  the  name  given  to  the  fat  extracted  from  the 
solid  fat  or  "suet"  of  cattle,  sheep  or  horses.  The  quality 
varies  greatly,  depending  upon  the  seasons  of  the  year, 
the  food  and  age  of  the  animal  and  the  method  of  ren- 
dering. It  comes  to  the  market  under  the  distinction  of 
edible  and  inedible,  a  further  distinction  being  made  in 
commerce  as  beef  tallow,  mutton  tallow  or  horse  tallow. 
The  better  quality  is  white  and  bleaches  whiter  upon  ex- 
posure to  air  and  light,  though  it  usually  has  a  yellowish 
tint,  a  well  defined  grain  and  a  clean  odor.  It  consists 
chiefly  of  stearin,  palmitin  and  olein.  Tallow  is  by  far  the 
most  extensively  used  and  important  fat  in  the  making 
of  soap. 

In  the  manufacture  of  soaps  for  toilet  purposes,  it  is 
usually  necessary  to  produce  as  white  a  product  as  pos- 
sible. In  order  to  do  this  it  often  is  necessary  to  bleach 
the  tallow  before  saponification.  The  method  usually  em- 
ployed is  the  Fuller's  Earth  process. 

FULLER'S  EARTH  PROCESS  FOR  BLEACHING  TALLOW. 
From  one  to  two  tons  of  tallow  are  melted  out  into  the 
bleaching  tank.  This  tank  is  jacketed,  made  of  iron  and 
provided  with  a  good  agitator  designed  to  stir  up  sediment 
or  a  coil  provided  with  tangential  downward  opening  per- 
forations and  a  draw-off  cock  at  the  bottom.  The  coil  is 
the  far  simpler  arrangement,  more  cleanly  and  less  likely 
to  cause  trouble.  By  this  arrangement  compressed  air 
which  is  really  essential  in  the  utilization  of  the  press 
(see  later)  is  utilized  for  agitation.  A  dry  steam  coil  in 
an  ordinary  tank  may  be  employed  in  place  of  a  jacketed 
tank,  which  lessens  the  cost  of  installation. 


RAW  MATERIALS 

The  tallow  in  the  bleaching  tank  is  heated  to  180°  F. 
(82°  C.)  and  ten  pounds  of  dry  salt  per  ton  of  fat  used 
added  and  thoroughly  mixed  by  agitation.  This  addition 
coagulates  any  albumen  and  dehydrates  the  fat.  The 
whole  mass  is  allowed  to  settle  over  night  where  possible, 
or  for  at  least  five  hours.  Any  brine  which  has  separated  is 
drawn  off  from  the  bottom  and  the  temperature  of  the 
fat  is  then  raised  to  160°  F.  (71°  C.). 

Five  per  cent,  of  the  weight  of  the  tallow  operated 
upon,  of  dry  Fuller's  earth  is  now  added  and  the  whole 
mass  agitated  from  twenty  to  thirty  minutes. 

The  new  bleached  fat,  containing  the  Fuller's  earth  is 
pumped  directly  to  a  previously  heated  filter  press  and 
the  issuing  clear  oil  run  directly  to  the  soap  kettle. 

One  of  the  difficulties  experienced  in  the  process  is  the 
heating  of  the  press  to  a  temperature  sufficient  to  prevent 
solidification  of  the  fat  without  raising  the  press  to  too 
great  a  temperature.  To  overcome  this  the  first  plate  is 
heated  by  wet  steam.  Air  delivered  from  a  blower  and 
heated  by  passage  through  a  series  of  coils  raised  to  a 
high  temperature  by  ^external  application  of  heat  (super- 
heated steam)  is  then  substituted  for  the  steam.  The 
moisture  produced  by  the  condensation  of  the  steam  is 
vaporized  by  the  hot  air  and  carried  on  gradually 'to  each 
succeeding  plate  where  it  again  condenses  and  vaporizes. 
In  this  way  the  small  quantity  of  water  is  carried  through 
the  entire  press,  raising  its  temperature  to  80°-100°  C 
This  temperature  is  subsequently  maintained  by  the 
passage  of  hot  air.  By  this  method  of  heating  the  poor 
conductivity  of  hot  air  is  overcome  through  the  inter- 
mediary action  of  a  liquid  vapor  and  the  latent  heat  of 
steam  is  utilized  to  obtain  the  initial  rise  in  temperature. 
To  heat  a  small  press  economically  where  conditions  are 
such  that  a  large  output  is  not  required  the  entire  press 


SOAP-MAKING    MANUAL 

may  be  encased  in  a  small  wooden  house  which  can  be 
heated  by  steam  coils.  The  cake  in  the  press  is  heated  for 
some  time  after  the  Alteration  is  complete  to  assist  drain- 
age. After  such  treatment  the  cake  should  contain  ap- 
proximately 15  per  cent,  fat  and  25  per  cent,  water.  The 
cake  is  now  removed  from  the  press  and  transferred  to  a 
small  tank  where  it  is  treated  with  sufficient  caustic  soda 
to  convert  the  fat  content  into  soap. 

Saturated  brine  is  then  added  to  salt  out  the  soap,  the 
Fuller's  earth  is  allowed  to  settle  to  the  bottom  of  the 
tank  and  the  soap  which  solidifies  after  a  short  time  is 
skimmed  off  to  be  used  in  a  cheap  soap  where  color  is 
not  important.  The  liquor  underneath  may  also  be  run 
off  without  disturbing  the  sediment  to  be  used  in  grain- 
ing a  similar  cheap  soap.  The  waste  Fuller's  earth  con- 
tains about  0.1  to  0.3  per  cent,  of  fat. 

METHOD  FOR  FURTHER  IMPROVEMENT  OF  COLOR. 

A  further  improvement  of  the  color  of  the  tallow  may 
be  obtained  by  freeing  it  from  a  portion  of  its  free  fatty 
acids,  either  with  or  without  previous  Fuller's  earth 
bleaching. 

To  carry  out  this  process  the  melted  fat  is  allowed  to 
settle  and  as  much  water  as  possible  taken  off.  The  tem- 
perature is  then  raised  to  160°  F.  with  dry  steam  and 
enough  saturated  solution  of  soda  ash  added  to  remove 
0.5  per  cent,  of  the  free  fatty  acids,  while  agitating  the 
mass  thoroughly  mechanically  or  by  air.  The  agitation 
is  continued  ten  minutes,  the  whole  allowed  to  settle  for 
two  hours  and  the  foots  drawn  off.  The  soap  thus  formed 
entangles  a  large  proportion  of  the  impurities  of  the  fat. 

VEGETABLE    OILS. 

Coceanut  Oil,  as  the  name  implies,  is  obtained  from  the 
fruit  of  the  cocoanut  palm.  This  oil  is  a  solid,  white  fat  at 
ordinary  temperature,  having  a  bland  taste  and  a  charac- 

6 


RAW  MATERIALS 

teristic  odor.  It  is  rarely  adulterated  and  is  very  readily 
saponified.  In  recent  years  the  price  of  this  oil  has  in- 
creased materially  because  cocoanut  oil  is  now  being  used 
extensively  for  edible  purposes,  especially  in  the  making  of 
oleomargarine.  Present  indications  are  that  shortly  very 
little  high  grade  oil  will  be  employed  for  soap  manufacture 
since  the  demand  for  oleomargarine  is  constantly  increas- 
ing and  since  new  methods  of  refining  the  oil  for  this  pur- 
pose are  constantly  being  devised. 

The  oil  is  found  in  the  market  under  three  different 
grades:  (1)  Cochin  cocoanut  oil,  the  choicest  oil  comes 
from  Cochin  (Malabar).  This  product,  being  more  care- 
fully cultivated  and  refined  than  the  other  grades,  is 
whiter,  cleaner  and  contains  a  smaller  percentage  of  free 
acid.  (2)  Ceylon  cocoanut  oil,  coming  chiefly  from  Cey- 
lon, is  usually  of  a  yellowish  tint  and  more  acrid  in  odor 
than  Cochin  oil.  (3)  Continental  cocoanut  oil  (Copra, 
Freudenberg)  is  obtained  from  the  dried  kernels,  the  copra, 
which  are  shipped  to  Europe  in  large  quantities,  where  the 
oil  is  extracted.  These  dried  kernels  yield  60  to  70  per 
cent  oil.  This  product  is  generally  superior  to  the  Ceylon 
oil  and  may  be  used  as  a  very  satisfactory  substitute  for 
Cochin  oil,  in  soap  manufacture,  provided  it  is  low  in  free 
acid  and  of  good  color.  The  writer  has  employed  it  satis- 
factorily in  the  whitest  and  finest  of  toilet  soaps  without 
being  able  to  distinguish  any  disadvantage  to  the  Cochin 
oil.  Since  continental  oil  is  usually  cheaper  than  Cochin 
oil,  it  is  advisable  to  use  it,  as  occasion  permits. 

Cocoanut  oil  is  used  extensively  in  toilet  soap  making, 
usually  in  connection  with  tallow.  When  used  alone 
the  soap  made  from  this  oil  forms  a  lather,  which  comes 
up  rapidly  but  which  is  fluffy  and  dries  quickly.  A  pure 
tallow  soap  lathers  very  much  slower  but  produces  a  more 
lasting  lather.  Thus  the  advantage  of  using  cocoanut  oil 


SOAP-MAKING    MANUAL 

in  soap  is  seen.  It  is  further  used  in  making  a  cocoanut 
oil  soap  by  the  cold  process  also  for  "fake"  or  filled  soaps. 
The  fatty  acid  content  readily  starts  the  saponification 
which  takes  place  easily  with  a  strong  lye  (25°-35°  B.). 
Where  large  quantities  of  the  oil  are  saponified  care  must 
be  exercised  as  the  soap  formed  suddenly  rises  or  puffs 
up  and  may  boil  over.  Cocoanut  oil  soap  takes  up  large 
quantities  of  water,  cases  having  been  cited  where  a  500 
per  cent,  yield  has  been  obtained.  This  water  of  course 
dries  out  again  upon  exposure  to  the  air.  The  soap  is 
harsh  to  the  skin,  develops  rancidity  and  darkens  readily. 

Palm  Kernel  Oil,  which  is  obtained  from  the  kernels  of 
the  palm  tree  of  West  Africa,  is  used  in  soap  making  to  re- 
place cocoanut  oil  where  the  lower  price  warrants  its  use. 
It  resembles  cocoanut  oil  in  respect  to  saponification  and 
in  forming  a  very  similar  soap.  Kernel  oil  is  white  in 
color,  has  a  pleasant  nutty  odor  when  fresh,  but  rapidly 
develops  free  acid,  which  runs  to  a  high  percentage. 

Palm  Oil  is  produced  from  the  fruit  of  the  several  species 
of  the  palm  tree  on  the  western  coast  of  Africa  generally, 
but  also  in  the  Philippines.  The  fresh  oil  has  a  deep  orange 
yellow  tint  not  destroyed  by  saponification,  a  sweetish  taste 
and  an  odor  of  orris  root  or  violet  which  is  also  imparted 
to  soap  made  from  it.  The  methods  by  which  the  natives 
obtain  the  oil  are  crude  and  depend  upon  a  fermentation,  or 
putrefaction.  Large  quantities  are  said  to  be  wasted  be- 
cause of  this  fact.  The  oil  contains  impurities  in  the  form 
of  fermentable  fibre  and  albuminous  matter,  and  conse- 
quently develops  free  fatty  acid  rapidly.  Samples  tested 
for  free  acid  have  been  found  to  have  hydrolized  completely 
and  one  seldom  obtains  an  oil  with  low  acid  content 
Because  of  this  high  percentage  of  free  fatty  acid,  the 
glycerine  yield  is  small,  though  the  neutral  oil  should 
produce  approximately  12  per  cent,  glycerine.  Some 

S 


RAW  MATERIALS 

writers  claim  that  glycerine  exists  in  the  free  state  in  palm 
oil.  The  writer  has  washed  large  quantities  of  the  oil  and 
analyzed  the  wash  water  for  glycerine.  The  results  showed 
that  the  amount  present  did  not  merit  its  recovery.  Most 
soap  makers  do  not  attempt  to  recover  the  glycerine 
from  this  oil,  when  used  alone  for  soap  manufacture. 

There  are  several  grades  of  palm  oil  in  commerce,  but 
in  toilet  soap  making  it  is  advisable  to  utilize  only  Lagos 
palm  oil,  which  is  the  best  grade.  Where  it  is  desired  tc 
maintain  the  color  of  the  soap  this  oil  produces,  a  small 
quantity  of  the  lower  or  "brass"  grade  of  palm  oil  may  be 
used,  as  the  soap  made  from  the  better  grades  of  oil 
gradually  bleaches  and  loses  its  orange  yellow  color. 

Palm  oil  produces  a  crumbly  soap  which  cannot  readily 
be  milled  and  is  termed  "short."  When  used  with  tallow 
and  cocoanut  oil,  or.  20  to  25  per  cent,  cocoanut  oil,  it 
produces  a  very  satisfactory  toilet  soap.  In  the  saponifi- 
cation  of  palm  oil  it  is  not  advisable  to  combine  it  with 
tallow  in  the  kettle,  as  the  two  do  not  readily  mix. 

Since  the  finished  soap  has  conveyed  to  it  the  orange 
color  of  the  oil,  the  oil  is  bleached  before  saponification. 
Oxidation  readily  destroys  the  coloring  matter,  while  heat 
and  light  assist  materially.  The  methods  generally  em- 
ployed are  by  the  use  of  oxygen  developed  by  bichromates 
and  hydrochloric  acid  and  the  direct  bleaching  through 
the  agency  of  the  oxygen  of  the  air. 

CHROME  BLEACHING  OF  PALM   OIL. 

The  chrome  process  of  bleaching  palm  oil  is  more  rapid 
and  the  oxygen  thus  derived  being  more  active  will  bleach 
oils  which  air  alone  cannot.  It  depends  upon  the  reaction : 

NaaCr2OT  +  8HC1  =  Cr2Cl«  +  2NaCl  +  7O. 
in  which  the  oxygen  is  the  active  principle.     In  practice  it 
is    found    necessary    to    use    an    excess    of    acid    over    that 
theoretically   indicated. 


SOAP-MAKING    MANUAL 

For  the  best  results  an  oil  should  be  chosen  containing 
under  2  per  cent,  impurities  and  a  low  percentage  of  free 
fatty  acids.  Lagos  oil  is  best  adapted  to  these  requirements. 
The  oil  is  melted  by  open  steam  from  a  jet  introduced 
through  the  bung,  the  melted  oil  and  condensed  water  run- 
ning to  the  store  tank  through  two  sieves  (about  ^  inch 
mesh)  to  remove  the  fibrous  material  and  gross  impurities 
The  oil  thus  obtained  contains  fine  earthy  and  fibrous  ma- 
terial and  vegetable  albuminous  matter  which  should  be 
removed,  as  far  as  possible,  since  chemicals  are  wasted  in 
their  oxidation  and  they  retard  the  bleaching.  This  is  best 
done  by  boiling  the  oil  for  one  hour  with  wet  steam  and 

10  per  cent,  solution  of  common  salt  (2  per  cent,  dry  salt 
on  weight  of  oil  used)    in  a  lead-lined  or  wooden  tank. 
After  settling  over  night  the  brine  and  impurities  are  re- 
moved by  running  from  a  cock  at  the  bottom  of  the  vat 
and  the  oil  is  run  out  into  the  bleaching  tank  through  an 

011  cock,  situated  about  seven  inches  from  the  bottom. 
The  bleaching  tank  is  a  lead-lined  iron  tank  of  the  ap- 
proximate   dimensions    of   4   feet    deep,    4    feet    long    and 
3^2    feet    wide,    holding    about    \l/2    tons.       The    charge 
is  one  ton.    A  leaden  outlet  pipe  is  fixed  at  the  bottom,  to 
which  is  attached  a  rubber  tube  closed  by  a  screw  clip.    A 
plug  also  is  fitted  into  the  lead  outlet  pipe  from  above. 
Seven  inches  above  the  lower  outlet  is  affixed  another  tap 
through  which  the  oil  is  drawn  off. 

The  tank  is  further  equipped  with  a  wet  steam  coil  and  a 
coil  arranged  to  allow  thorough  air  agitation,  both  coils 
being  of  lead.  A  good  arrangement  is  to  use  one  coil  to 
deliver  either  air  or  steam.  These  coils  should  extend  as 
nearly  as  possible  over  the  entire  bottom  of  the  tank  and 
have  a  number  of  small  downward  perforations,  so  as  to 
spread  the  agitation  throughout  the  mass. 

The  temperature  of  the  oil  is  reduced  by  passing  in  ail 
10 


RAW  MATERIALS 

to  110°  F.  and  40  pounds  of  fine  common  salt  per  ton  added 
through  a  sieve.  About  one-half  of  the  acid  (40  pounds 
of  concentrated  commercial  hydrochloric  acid)  is  now 
poured  in  and  this  is  followed  by  the  sodium  bichromate 
in  concentrated  solution,  previously  prepared  in  a  small 
lead  vat  or  earthen  vessel  by  dissolving  17  pounds  of  bi- 
chromate in  45  pounds  commercial  hydrochloric  acid.  This 
solution  should  be  added  slowly  and  should  occupy  three 
hours,  the  whole  mass  being  thoroughly  agitated  with  air 
during  the  addition  and  for  one  hour  after  the  last  of  the 
bleaching  mixture  has  been  introduced.  The  whole  mix- 
ture is  now  allowed  to  settle  for  one  hour  and  the  ex- 
hausted chrome  liquors  are  then  run  off  from  the  lowei 
pipe  to  a  waste  tank.  About  40  gallons  of  water  are  now 
run  into  the  bleached  oil  and  the  temperature  raised  by 
open  steam  to  150°  to  160°  F.  The  mass  is  then  allowed 
to  settle  over  night. 

One  such  wash  is  sufficient  to  remove  the  spent  chrome 
liquor  completely,  provided  ample  time  is  allowed  for 
settling.  A  number  of  washings  given  successively  with 
short  periods  of  settling  do  not  remove  the  chrome  liquors 
effectually.  The  success  of  the  operation  depends  en- 
tirely upon  the  completeness  of  settling. 

The  wash  water  is  drawn  off  as  before  and  the  clear 
oil  run  to  storage  tanks  or  to  the  soap  kettle  through  the 
upper  oil  cock. 

The  waste  liquors  are  boiled  with  wet  steam  and  the  oil 
skimmed  from  the  surface,  after  which  the  liquors  are  run 
out  through  an  oil  trap. 

By  following  the  above  instructions  carefully  it  is  pos- 
sible to  bleach  one  ton  of  palm  oil  with  17  pounds  of  bi- 
chromate of  soda  and  85  pounds  hydrochloric  acid. 

The  spent  liquors  should  be  a  bright  green  color.  Should 
they  be  of  a  yellow  or  brownish  shade  insufficient  acid  has 

11 


SOAP-MAKING     MANUAL 

been  allowed  and  more  must  be  added  to  render  the  whole 
of  the  oxygen  available. 

If  low  grade  oils  are  being  treated  more  chrome  will  be 
necessary,  the  amount  being  best  judged  by  conducting  the 
operation  as  usual  and  after  the  addition  of  the  bichro- 
mate, removing  a  sample  of  the  oil,  washing  the  sample 
and  noting  the  color  of  a  rapidly  cooled  sample. 

A  little  practice  will  enable  the  operator  to  judge  the 
correspondence  between  the  color  to  be  removed  and  the 
amount  of  bleaching  mixture  to  be  added. 

To  obtain  success  with  this  process  the  method  of  work- 
ing given  must  be  adhered  to  even  in  the  smallest  detail. 
This  applies  to  the  temperature  at  which  each  operation 
is  carried  out  particularly. 

AIR  BLEACHING   OF   PALM    OIL. 

The  method  of  conducting  this  process  is  identical  with 
the  chrome  process  to  the  point  where  the  hydrochloric  acid 
is  to  be  added  to  the  oil.  In  this  method  no  .acid  or 
chrome  is  necessary,  as  the  active  bleaching  agent  is  the 
oxygen  of  the  air. 

The  equipment  is  similar  to  that  of  the  former  process, 
except  that  a  wooden  tank  in  which  no  iron  is  exposed  will 
suffice  to  bleach  the  oil  in.  The  process  depends  in  rapid- 
ity upon  the  amount  of  air  blown  through  the  oil  and  its 
even  distribution.  Iron  should  not  be  present  or  exposed 
to  the  oil  during  bleaching,  as  it  retards  the  process  con- 
siderably. 

After  the  impurities  have  been  removed,  as  outlined 
under  the  chrome  process,  the  temperature  of  the  oil  is 
raised  by  open  steam  to  boiling.  The  steam  is  then  shut 
off  and  air  allowed  to  blow  through  the  oil  until  it  is  com- 
pletely bleached,  the  temperature  being  maintained  above 
150°  F.  by  occasionally  passing  in  steam.  Usually  a  ton 
of  oil  is  readily  and  completely  bleached  after  the  air  has 

12 


RAW  MATERIALS 

been  passed  through  it  for  18  to  20  hours,  provided  the 
oil  is  thoroughly  agitated  by  a  sufficient  flow  of  air. 

If  the  the  oil  has  been  allowed  to  settle  over  night,  it  is 
advisable  to  run  off  the  condensed  water  and  impurities 
by  the  lower  cock  before  agitating  again  the  second  day. 

When  the  oil  has  been  bleached  to  the  desired  color, 
which  can  be  determined  by  removing  a  sample  and  cool- 
ing, the  mass  is  allowed  to  settle,  the  water  run  off  to  a 
waste  tank  from  which  any  oil  carried  along  may  be 
skimmed  off  and  the  supernatant  clear  oil  run  to  the  stor- 
age or  soap  kettle. 

In  bleaching  by  this  process,  while  the  process  consumes 
more  time  and  is  not  as  efficient  in  bleaching  the  lower 
grade  oils,  the  cost  of  bleaching  is  less  and  with  a  good 
oil  success  is  more  probable,  as  there  is  no  possibility  of 
any  of  the  chrome  liquors  being  present  in  the  oil.  These 
give  the  bleached  oil  a  green  tint  when  the  chrome  method 
is  improperly  conducted  and  they  are  not  removed. 

Instead  of  blowing  the  air  through  it,  the  heater  oil  may 
be  brought  into  contact  with  the  air,  either  by  a  paddle 
wheel  arrangement,  which,  in  constantly  turning,  brings 
the  oil  into  contact  with  the  air,  or  by  pumping 
the  heated  oil  into  an  elevated  vessel,  pierced  with  numer- 
ous fine  holes  from  which  the  oil  continously  flows  back 
into  the  vessel  from  which  the  oil  is  pumped.  While  in 
these  methods  air,  light  and  heat  act  simultaneously  in  the 
bleaching  of  the  oil,  the  equipment  required  is  too  cum- 
bersome to  be  practical. 

Recent  investigations1  in  bleaching  palm  oil  by  oxygen 
have  shown  that  not  only  the  coloring  matter  but  the  oil 
itself  was  affected.  In  bleaching  palm  oil  for  30  hours 
with  air  the  free  fatty  acid  content  rose  and  titer  decreased 
considerably. 

iSeifensieder  Zeit,  1913.  40,  p.  687,  724,  740. 
13 


SOAP-MAKING    MANUAL 

Olive  Oil,  which  comes  from  the  fruit  of  the  olive  trees, 
varies  greatly  in  quality,  according  to  the  method  by  which 
it  is  obtained  and  according  to  the  tree  bearing  the  fruit 
Three  hundred  varieties  are  known  in  Italy  alone.  Since 
the  larger  portion  of  olive  oil  is  used  for  edible  purposes, 
a  lower  grade,  denatured  oil,  denatured  because  of  the 
tariff,  is  used  for  soap  manufacture  in  this  country.  The 
oil  varies  in  color  from  pale  green  to  golden  yellow.  The 
percentage  of  free  acid  in  this  oil  varies  greatly,  though  the 
oil  does  not  turn  rancid  easily.  It  is  used  mainly  in  the 
manufacture  of  white  castile  soap. 

Olive  oil  foots,  which  is  the  oil  extracted  by  solvents  after 
the  better  oil  is  expressed,  finds  its  use  in  soap  making 
mostly  in  textile  soaps  for  washing  and  dyeing  silks  and 
in  the  production  of  green  castile  soaps. 

Other  oils,  as  poppy  seed  oil,  sesame  oil,  cottonseed  oil, 
rape  oil,  peanut  (arachis)  oil,  are  used  as  adulterants  for 
olive  oil,  also  as  substitutes  in  the  manufacture  of  castile 
soap,  since  they  are  cheaper  than  olive  oil. 

Cottonseed  Oil  is  largely  used  in  the  manufacture  of 
floating  and  laundry  soaps.  It  may  be  used  for  toilet 
soaps  where  a  white  color  is  not  desired,  as  yellow  spots 
appear  on  a  finished  soap  in  which  it  has  been  used  after 
having  been  in  stock  a  short  time. 

Corn  Oil  and  Soya  Bean  Oil  are  also  used  to  a  slight  ex- 
tent in  the  manufacture  of  toilet  soaps,  although  the  oils 
form  a  soap  of  very  little  body.  Their  soaps  also  spot 
yellow  on  aging. 

Corn  oil  finds  its  greatest  use  in  the  manufacture  of 
soap  for  washing  automobiles.  It  is  further  employed  for 
the  manufacture  of  cheap  liquid  soaps. 

Fatty  Acids  are  also  used  extensively  in  soap  manufac- 
ture. While  the  soap  manufacturer  prefers  to  use  a  neutral 
oil  or  fat,  since  from  these  the  by-product  glycerine  is 

14 


RAW  MATERIALS 

obtained,  circumstances  arise  where  it  is  an  advantage  to 
use  the  free  fatty  acids.  Red  oil  (oleic  acid,  elaine)  and 
stearic  acid  are  the  two  fatty  acids  most  generally  bought 
for  soap  making.  In  plants  using  the  Twitchell  process, 
which  consists  in  splitting  the  neutral  fats  and  oils  into 
fatty  acids  and  glycerine  by  dilute  sulphuric  acid  and  pro- 
ducing their  final  separation  by  the  use  of  so-called  aromatic 
sulphonic  acids,  these  fatty  acids  consisting  of  a  mixture  of 
oleic,  stearic,  palmitic  acids,  etc.,  are  used  directly  after 
having  been  purified  by  distillation,  the  glycerine  being  ob- 
tained from  evaporating  the  wash  water. 

Oleic  acid  (red  oil)  and  stearic  acid  are  obtained  usual- 
ly by  the  saponification  of  oils,  fats  and  greases  by  acid, 
lime  or  water  under  pressure  or  Twitchelling.  The 
fatty  acids  thus  are  freed  from  their  combination  with 
glycerine  and  solidify  upon  cooling,  after  which  they  are 
separated  from  the  water  and  pressed  at  a  higher  or  lower 
temperature.  The  oleic  acid,  being  liquid  at  ordinary 
temperature,  together  with  some  stearic  and  palmitic  acid, 
is  thus  pressed  out.  These  latter  acids  are  usually  sepa- 
rated by  distillation,  combined  with  the  press  cake  further 
purified  and  sold  as  stearic  acid. 

The  red  oil,  sometimes  called  saponified  red  oil,  is  often 
semi-solid,  resembling  a  soft  tallow,  due  to  the  presence 
of  stearic  acid.  The  distilled  oils  are  usually  clear,  vary- 
ing in  color  from  light  to  a  deep  brown.  Stearic  acid, 
which  reaches  the  trade  in  slab  form,  varies  in  quality 
from  a  soft  brown,  greasy,  crumbly  solid  of  unpleasant 
odor  to  a  snow  white,  wax-like,  hard,  odorless  mass.  The 
quality  of  stearic  acid  is  best  judged  by  the  melting  point, 
since  the  presence  of  any  oleic  acid  lowers  this.  The  melt- 
ing point  of  the  varieties  used  in  soap  manufacture  usually 
ranges  from  128°  to  132°  F.  Red  oil  is  used  in  the  manu- 
facture of  textile  soaps,  replacing  olive  oil  foots  soap  for 

15 


SOAP-MAKING    MANUAL 

this  purpose,  chlorophyll  being  used  to  color  the  soap 
green.  Stearic  acid,  being  the  hard  firm  fatty  acid,  may  be 
used  in  small  quantities  to  give  a  better  grade  of  soap  body 
and  finish.  In  adding  this  substance  it  should  always 
be  done  in  the  crutcher,  as  it  will  not  mix  in  the  kettle. 
It  finds  its  largest  use  for  soap,  however,  in  the  manu- 
facture of  shaving  soaps  and  shaving  creams,  since  it 
produces  the  non-drying  creamy  lather  so  greatly  desired 
for  this  purpose.  Both  red  oil  and  stearic  acid  being  fatty 
acids,  readily  unite  with  the  alkali  carbonates,  carbon  diox- 
-ide  being  formed  in  the  reaction  and  this  method  is  ex- 
tensively used  in  the  formation  of  soap  from  them. 

RANCIDITY   OF   OILS   AND   FATS. 

Rancidity  in  neutral  oils  and  fats  is  one  of  the  problems 
the  soap  manufacturer  has  to  contend  with.  The  mere 
saying  that  an  oil  is  rancid  is  no  indication  of  its  being 
high  in  free  acid.  The  two  terms  rancidity  and  acidity  are 
usually  allied.  Formerly,  the  acidity  of  a  fat  was  looked 
upon  as  the  direct  measure  of  its  rancidity.  This  idea  is 
still  prevalent  in  practice  and  cannot  be  too  often  stated 
as  incorrect.  Fats  and  oils  may  be  acid,  or  rancid,  or  acid 
and  rancid.  In  an  acid  fat  there  has  been  a  hydrolysis  of 
the  fat  and  it  has  developed  a  rather  high  percentage  of 
free  acid.  A  rancid  fat  is  one  in  which  have  been  de- 
veloped compounds  of  an  odoriferous  nature. .  An  acid  and 
rancid  fat  is  one  in  which  both  free  acid  and  organic  com- 
pounds of  the  well  known  disagreeable  odors  have  been 
produced. 

It  cannot  be  definitely  stated  just  how  this  rancidity 
takes  place,  any  more  than  just  what  are  the  chemical 
products  causing  rancidity.  The  only  conclusion  that  one 
may  draw  is  that  the  fats  are  first  hydrolyzed  or  split  up 
into  glycerine  and  free  fatty  acids.  This  is  followed  by 
an  oxidation  of  the  products  thus  formed. 

16 


RAW  MATERIALS 

Moisture,  air,  light,  enzymes  (organized  ferments)  and 
bacteria  are  all  given  as  causes  of  rancidity. 

It  seems  very  probable  that  the  initial  splitting  of  the 
fats  is  caused  by  enzymes,  which  are  present  in  the  seeds 
and  fruits  of  the  vegetable  oils  and  tissue  of  animal  fats, 
in  the  presence  of  moisture.  Lewkowitsch  strongly  em- 
phasizes this  point  and  he  is  substantiated  in  his  idea  by 
other  authorities.  Others  hold  that  bacteria  or  micro- 
organisms are  the  cause  of  this  hydrolysis,  citing  the  fact 
that  they  have  isolated  various  micro-organisms  from 
various  fats  and  oils.  The  acceptance  of  the  bacterial  ac- 
tion would  explain  the  various  methods  of  preservation  of 
oils  and  fats  by  the  use  of  antiseptic  preparations.  It  can- 
not, however,  be  accepted  as  a  certainty  that  bacteria  cause 
the  rancidity  of  fats. 

The  action  of  enzymes  is  a  more  probable  explanation. 

The  hydrolysis  of  fats  and  oils  is  accelerated  when  they 
are  allowed  to  remain  for  some  time  in  the  presence  of 
organic  non-fats.  Thus,  palm  oil,  lower  grades  of  olive 
oil,  and  tallow,  which  has  been  in  contact  with  the  animal 
tissue  for  a  long  time,  all  contain  other  nitrogenous  matter 
and  exhibit  a  larger  percentage  of  free  fatty  acid  than  the 
oils  and  fats  not  containing  such  impurities. 

Granting  this  initial  splitting  of  the  fat  into  free  fatty 
acids  and  glycerine,  this  is  not  a  sufficient  explanation.  The 
products  thus  formed  must  be  acted  upon  by  air  and  light. 
It  is  by  the  action  of  these  agents  that  there  is  a  further 
action  upon  the  products,  and  from  this  oxidation  we  as- 
certain by  taste  and  smell  (chemical  means  are  still  unable 
to  define  rancidity)  whether  or  not  a  fat  is  rancid.  While 
some  authorities  have  presumed  to  isolate  some  of  these 
products  causing  rancidity,  we  can  only  assume  the  presence 
of  the  various  possible  compounds  produced  by  the  action 

17 


SOAP-MAKING    MANUAL 

of  air  and  light  which  include  oxy  fatty  acids,  lactones,  al- 
cohols, esters,  aldehydes  and  other  products. 

The  soap  manufacturer  is  interested  in  rancidity  to  the 
extent  of  the  effect  upon  the  finished  soap.  Rancid  fats 
form  darker  soaps  than  fats  in  the  neutral  state,  and  very 
often  carry  with  them  the  disagreeable  odor  of  a  rancid  oil. 
Further,  a  rancid  fat  or  oil  is  usually  high  in  free  acid.  It 
is  by  no  means  true,  however,  that  rancidity  is  a  meas- 
ure for  acidity,  for  as  has  already  been  pointed  out,  an 
oil  may  be  rancid  and  not  high  in  free  acid. 

The  percentage  of  free  fatty  acid  is  of  even  greater 
importance  in  the  soap  industry.  The  amount  of  glycerine 
yield  is  dependent  upon  the  percentage  of  free  fatty  acid 
and  is  one  of  the  criterions  of  a  good  fat  or  oil  for  soap 
stock. 

PREVENTION    OF   RANCIDITY. 

Since  moisture,  air,  light  and  enzymes,  produced  by  the 
presence  of  organic  impurities,  are  necessary  for  the  ran- 
cidity of  a  fat  or  oil,  the  methods  of  preventing  rancidity 
are  given.  Complete  dryness,  complete  purification  of  fats 
and  oils  and  storage  without  access  of  air  or  light  are  de- 
sirable. Simple  as  these  means  may  seem,  they  can  only 
be  approximated  in  practice.  The  most  difficult  problem  is 
the  removal  of  the  last  trace  of  moisture.  Impurities  may 
be  lessened  very  often  by  the  use  of  greater  care.  In  stor- 
ing it  is  well  to  store  in  closed  barrels  or  closed  iron 
tanks  away  from  light,  as  it  has  been  observed  that  oils 
and  fats  in  closed  receptacles  become  rancid  less  rapidly 
than  those  in  open  ones,  even  though  this  method  of  stor- 
ing is  only  partially  attained.  Preservatives  are  also  used, 
but  only  in  edible  products,  where  their  effectiveness  is  an 
open  question. 

CHEMICAL  CONSTANTS  OF  OILS  AND  FATS. 

Besides  the  various  physical  properties  of  oils  and  fats, 

18 


RAW  MATERIALS 

such  as  color,  specific  gravity,  melting  point,  solubility,  etc., 
they  may  be  distinguished  chemically  by  a  number  of 
chemical  constants.  These  are  the  iodine  number,  the  acetyl 
value,  saponification  number,  Reichert-Meissl  number  for 
volatile  acids,  Hehner  number  for  insoluble  acids.  These 
constants,  while  they  vary  somewhat  with  any  particular 
oil  or  fat,  are  more  applicable  to  the  edible  products  and 
are  criterions  where  any  adulteration  of  fat  or  oil  is  sus- 
pected. The  methods  of  carrying  out  the  analyses  of  oils 
and  fats  to  obtain  these  constants  are  given  in  the  various 
texts*  on  oils  and  fats,  and  inasmuch  as  they  are  not  of 
great  importance  to  the  soap  industry  they  are  merely  men- 
tioned here. 

OIL   HARDENING  OR   HYDROGEN ATING. 

It  is  very  well  known  that  oils  and  fats  vary  in  con- 
sistency and  hardness,  depending  upon  the  glycerides 
forming  same.  Olein,  a  combination  of  oleic  acid  and 
glycerine,  as  well  as  oleic  acid  itself  largely  forms  the 
liquid  portion  of  oils  and  fats.  Oleic  acid  (QsH^Oa)  is  an 
unsaturated  acid  and  differs  from  stearic  acid  QgHseO,), 
the  acid  forming  the  hard  firm  portion  of  oils  and  fats, 
by  containing  two  atoms  of -hydrogen  less  in  the  mole- 
cule. Theoretically  it  should  be  a  simple  matter  to  intro- 
duce two  atoms  of  hydrogen  into  oleic  acid  or  olein,  and 
by  this  mere  addition  convert  liquid  oleic  acid  and  olein 
into  solid  stearic  acid  and  stearine. 

For  years  this  was  attempted  and  all  attempts  to  apply 
the  well  known  methods  of  reduction  (addition  of  hydro- 
gen) in  organic  chemistry,  such  as  treatment  with  tin 
and  acid,  sodium  amalgam,  etc.,  were  unsuccessful.  In 
recent  years,  however,  it  has  been  discovered  that  in  the 
presence  of  a  catalyzer,  nickel  in  finely  divided  form 

•Official  Methods,  see  Bull.  107,  A.  O.  A.  C.,  U.  S.  Dept.  Agricult 
19 


SOAP-MAKING     MANUAL 

or  the  oxides  of  nickel  are  usually  employed,  the  process 
of  hydrogenating  an  oil  is  readily  attained  upon  a  prac- 
tical basis. 

The  introduction  of  hardened  oils  has  opened  a  new 
source  of  raw  material  for  the  soap  manufacturer  in 
that  it  is  now  possible  to  use  oils  in  soap  making  which 
were  formerly  discarded  because  of  their  undesirable 
odors.  Thus  fish  or  train  oils  which  had  up  to  the  time 
of  oil  hydrogenating  resisted  all  attempts  of  being  per- 
manently deodorized,  can  now  be  employed  very  satis- 
factorily for  soap  manufacture.  A  Japanese  chemist, 
Tsujimoto1  has  shown  that  fish  oils  contain  an  unsatu- 
rated  acid  of  the  composition  dsH^CX,  for  which  he  pro- 
posed the  name  clupanodonic  acid.  By  the  catalytic  hard- 
ening of  train  oils  this  acid  passes  to  stearic  acid  and  the 
problem  of  deodorizing  these  oils  is  solved.2 

At  first  the  introduction  of  hardened  oils  for  soap 
manufacture  met  with  numerous  objections,  due  to  the 
continual  failures  of  obtaining  a  satisfactory  product  by 
the  use  of  same.  Various  attempts  have  now  shown  that 
these  oils,  particularly  hardened  train  oils,  produce 
extraordinarily  useful  materials  for  soap  making.  These 
replace  expensive  tallow  and  other  high  melting  oils.  It 
is  of  course  impossible  to  employ  hardened  oils  alone,  as 
a  soap  so  hard  would  thus  be  obtained  that  it  would 
be  difficultly  soluble  in  water  and  possess  very  little  lather- 
ing quality.  By  the  addition  of  20-25%  of  tallow  oil  or 
some  other  oil  forming  a  soft  soap  a  very  suitable  soap 
for  household  use  may  be  obtained.  Ribot3  discusses  this 
matter  fully.  Hardened  oils  readily  saponify,  may  be 


ijourn.    Coll.    of   Engin.   Tokyo   Imper.   Univ.    (1906),    p.    1.      Abs. 
Chem.  Revue  f.  d.  Fett-u.  Harz,  Ind.  16,  p.  84;  20,  p.  8. 

7  Meyerheim — Fort,  der  Chem.,  Physik.  und  Physik.  Chem.   (1913), 


J.   6,    p.    293-307. 
8  Seifs. 


Ztg.    (1913),  40,  p.   142. 

20 


RAW  MATERIALS 

perfumed  without  any  objections  and  do  not  impart  any 
fishy  odor  to  an  article  washed  with  same.  Meyerheim* 
states  that  through  the  use  of  hydrogenated  oils  the  hard- 
ness of  soap  is  extraordinarily  raised,  so  that  soap  made 
from  hardened  cottonseed  oil  is  twelve  times  as  hard  as 
the  soap  made  from  ordinary  cottonseed  oil.  This  soap 
is  also  said  to  no  longer  spot  yellow  upon  aging,  and  as 
a  consequence  of  its  hardness,  is  able  to  contain  a  con- 
siderably higher  content  of  rosin  through  which  lather- 
ing power  and  odor  may  be  improved.  Hardened  oils 
can  easily  be  used  for  toilet  soap  bases,  provided  they 
are  not  added  in  too  great  a  percentage. 

The  use  of  hardened  oils  is  not  yet  general,  but  there 
is  little  doubt  that  the  introduction  of  this  process  goes  a 
long  way  toward  solving  the  problem  of  cheaper  soap 
material  for  the  coap  making  industry. 

GREASE. 

Grease  varies  so  greatly  in  composition  and  consistency 
that  it  can  hardly  be  classed  as  a  distinctive  oil  or  fat. 
It  is  obtained  from  refuse,  bones,  hides,  etc.,  and  while 
it  contains  the  same  constituents  as  tallow,  the  olein  con- 
tent is  considerably  greater,  which  causes  it  to  be  more 
liquid  in  composition.  Grease  differs  in  color  from  an 
off-white  to  a  dark  brown.  The  better  qualities  are  em- 
ployed in  the  manufacture  of  laundry  and  chip  soap, 
while  the  poorer  qualities  are  only  fit  for  the  cheapest  of 
soaps  used  in  scrubbing  floors  and  such  purposes.  There 
is  usually  found  in  grease  a  considerable  amount  of  gluey 
matter,  lime  and  water.  The  percentage  of  free  fatty 
acid  is  generally  high. 

The  darker  grades  of  grease  are  bleached  before  be- 
ing used.  This  is  done  by  adding  a  small  quantity  of 
sodium  nitrate  to  the  melted  grease  and  agitating,  then 

*Loc.  cit. 

21 


SOAP-MAKING    MANUAL 

removing  the  excess  saltpeter  by  decomposing  with  sul- 
phuric acid.  A  better  method  of  refining,  however,  is  by 
distillation.  The  chrome  bleach  is  also  applicable. 

ROSIN   (COLOPHONY,  YELLOW  ROSIN,  RESINA). 

Rosin  is  the  residue  which  remains  after  the  distil- 
lation of  turpentine  from  the  various  species  of  pines. 
The  chief  source  of  supply  is  in  the  States  of  Georgia 
North  and  South  Carolina.  It  is  a  transparent,  amber 
colored  hard  pulverizable  resin.  The  better  grades  are 
light  in  color  and  known  as  water  white  (w.  w.)  and 
window  glass  (w.  g.).  These  are  obtained  from  a  tree 
which  has  been  tapped  for  the  first  year.  As  the  same 
trees  are  tapped  from  year  to  year,  the  product  becomes 
deeper  and  darker  in  color  until  it  becomes  almost  black. 

The  constituents  of  rosin  are  chiefly  (80-90%)  abietic 
acid  or  its  anhydride  together  with  pinic  and  sylvic 
acids.  Its  specific  gravity  is  1.07-1.08,  melting  point 
about  152.5  C,  and  it  is  soluble  in  alcohol,  ether,  benzine, 
carbon  disulfide,  oils,  alkalis  and  acetic  acid.  The  main  use 
of  rosin,  outside  of  the  production  of  varnishes,  is  in  the 
production  of  laundry  soaps,  although  a  slight  percentage 
acts  as  a  binder  and  fixative  for  perfumes  in  toilet  soaps  and 
adds  to  their  detergent  properties.  Since  it  is  mainly  com- 
posed of  acids,  it  readily  unites  with  alkaline  carbonates, 
though  the  saponification  is  not  quite  complete  and  the 
last  portion  must  be  completed  through  the  use  of  caustic 
hydrates,  unless  an  excess  of  10%  carbonate  over  the 
theoretical  amount  is  used.  A  lye  of  20°  B.  is  best 
adapted  to  the  saponification  of  rosin  when  caustic  hydrates 
are  employed  'for  this  purpose,  since  weak  lyes  cause 
frothing.  While  it  is  sometimes  considered  that  rosin 
is  an  adulterant  for  soap,  this  is  hardly  justifiable,  as  it 
adds  to  the  cleansing  properties  of  soap.  Soaps  contain- 

22 


RAW  MATERIALS 

ing  rosin  are  of  the  well  known  yellowish  color  common 
to  ordinary  laundry  soaps.  The  price  of  rosin  has  so 
risen  in  the  last  few  years  that  it  presents  a  problem  of 
cost  to  the  soap  manufacturer  considering  the  price  at 
which  laundry  soaps  are  sold. 

ROSIN     SAPONIFICATION. 

As  has  been  stated,  rosin  may  be  saponified  by  the  use 
of  alkaline  carbonates.  On  account  of  the  possibility  of 
the  soap  frothing  over,  the  kettle  in  which  the  operation 
takes  place  should  be  set  flush  with  the  floor,  which 
ought  to  be  constructed  of  cement.  The  kettle  itself  is 
an  open  one  with  round  bottom,  equipped  with  an  open 
steam  coil  and  skimmer  pipe,  and  the  open  portion  is 
protected  by  a  semi-circular  rail.  A  powerful  grid,  hav- 
ing a  3-inch  mesh,  covers  one-half  of  the  kettle,  the 
sharp  edges  protruding  upwards. 

The  staves  from  the  rosin  casks  are  removed  at  the 
edge  of  the  kettle,  the  rosin  placed  on  the  grid  and 
beaten  through  with  a  hammer  to  break  it  up  into  small 
pieces. 

To  saponify  a  ton  of  rosin  there  are  required  200  Ibs. 
soda  ash,  1,600  Ibs.  water  and  100  Ibs.  salt.  Half  the 
water  is  run  into  the  kettle,  boiled,  and  then  the  soda  ash 
and  half  the  salt  added.  The  rosin  is  now  added  through 
the  grid  and  the  mixture  thoroughly  boiled.  As  carbon 
dioxide  is  evolved  by  the  reaction  the  boiling  is  con- 
tinued for  one  hour  to  remove  any  excess  of  this  gas.  A 
portion  of  the  salt  is  gradually  added  to  grain  the  soap 
well  and  to  keep  the  mass  in  such  condition  as  to  favor 
the  evolution  of  gas.  The  remainder  of  the  water  is 
added  to  close  the  soap  and  boiling  continued  for  one 
or  two  hours  longer.  At  this  point  the  kettle  must  be 
carefully  watched  or  it  will  boil  over  through  the  further 

23 


SOAP-MAKING     MANUAL 

escape  of  carbon  dioxide  being  hindered.  The  mass, 
being  in  a  frothy  condition,  will  rapidly  settle  by  con- 
trolling the  flow  of  steam.  The  remaining  salt  is  then 
scattered  in  and  the  soap  allowed  to  settle  for  two  hours 
or  longer.  The  lyes  are  then  drained  off  the  top. 
If  the  rosin  soap  is  required  for  toilet  soaps,  it  is 
grained  a  second  time.  The  soap  is  now  boiled  with 
the  water  caused  by  the  condensation  of  the  steam,  which 
changes  it  to  a  half  grained  soap  suitable  for  pumping. 
A.  soap  thus  made  contains  free  soda  ash  0.15%  or  less, 
free  rosin  about  15%.  The  mass  is  then  pumped  to  the 
kettle  containing  the  soap  to  which  it  is  to  be  added  at 
the  proper  stage.  The  time  consumed  in  thus  saponifying 
rosin  is  about  five  hours. 

NAPHTHENIC   ACIDS. 

The  naphtha  or  crude  petroleum  of  the  various  prov- 
inces in  Europe,  as  Russia,  Galacia,  Alsace  and  Rou- 
mania  yield  a  series  of  bodies  of  acid  character  upon  re- 
fining which  are  designated  under  the  general  name  of 
naphthenic  acids.  These  acids  are  retained  in  solution 
in  the  alkaline  lyes  during  the  distillation  of  the  naphtha 
in  the  form  of  alkaline  naphthenates.  Upon  adding  di- 
lute sulphuric  acid  to  these  lyes  the  naphthenates  are 
decomposed  and  the  naphthenic  acids  float  to  the  sur- 
face in  an  oily  layer  of  characteristic  disagreeable  odor 
and  varying  from  yellow  to  brown  in  color1.  In  Russia 
particularly  large  quantities  of  these  acids  are  employed 
in  the  manufacture  of  soap. 

The  soaps  formed  from  naphthenic  acids  have  recently 
been  investigated2  and  found  to  resemble  the  soaps  made 
from  cocoanut  oil  and  palm  kernel  oil,  in  that  they  are 


Les  Matieres  Graisses  (1914),  7,  69,  p.  3367. 
Zeit.   f.   Angew.  Chem.    (1914),  27,   1,  p.  2-4. 

24 


RAW  MATERIALS 

difficult  to  salt  out  and  dissociate  very  slightly  with  water, 
The  latter  property  makes  them  valuable  in  textile  in- 
dustries when  a  mild  soap  is  required  as  a  detergent,  e.  g., 
in  the  silk  industry.  These  soaps  also  possess  a  high  solvent 
power  for  mineral  oils  and  emulsify  very  readily.  The 
mean  molecular  weight  of  naphthenic  acids  themselves  is 
very  near  that  of  the  fatty  acids  contained  in  cocoanut 
oil,  and  like  those  of  cocoanut  oil  a  portion  of  the  sepa- 
rated acids  are  volatile  with  steam.  The  iodine  number 
indicates  a  small  content  of  unsaturated  acids. 

That  naphthenic  acids  are  a  valuable  soap  material  is 
now  recognized,  but  except  in  Russia  the  soap  is  not 
manufactured  to  any  extent  at  the  present  time. 

ALKALIS. 

The  common  alkali  metals  which  enter  into  the  for- 
mation of  soap  are  sodium  and  potassium.  The  hy- 
droxides of  these  metals  are  usually  used,  except  in  the 
so  called  carbonate  saponification  of  free  fatty  acids  in 
which  case  sodium  and  potassium  carbonate  are  used.  .A 
water  solution  of  the  caustic  alkalis  is  known  as  lye,  and 
it  is  as  lyes  of  various  strengths  that  they  are  added 
to  oils  and  fats  to  form  soap.  The  density  or  weight  of 
a  lye  is  considerably  greater  than  that  of  water,  depend- 
ing upon  the  amount  of  alkali  dissolved,  and  its  weight 
is  usually  determined  by  a  hydrometer.  This  instrument  is 
graduated  by  a  standardized  scale,  and  while  all  hydro- 
meters should  read  alike  i»  a  liquid  of  known  specific 
gravity,  this  is  generally  not  the  case,  so  that  it  is  advisable 
to  check  a  new  hydrometer  for  accurate  work  against  one 
of  known  accuracy.  In  this  country  the  Baume  scale  has 
been  adopted,  while  in  England  a  different  graduation 
known  as  the  Twaddle  scale  is  used.  The  strength  of  a 
lye  or  any  solution  is  determined  by  the  distance  the  in- 

25 


SOAP-MAKING    MANUAL 

strument  sinks  into  the  solution,  and  we  speak  of  the 
strength  of  a  solution  as  so  many  degrees  Baume  or  Twad- 
dle which  are  read  to  the  point  where  the  meniscus  of  the 
lye  comes  on  the  graduated  scale.  Hydrometers  are 
graduated  differently  for  liquids  of  different  weights.  In 
the  testing  of  lyes  one  which  is  graduated  from  0°  to 
50°  B.  is  usually  employed. 

Caustic  soda  is  received  by  the  consumer  in  iron 
drums  weighing  approximately  700  Ibs.  each.  The  vari- 
ous grades  are  designated  as  60,  70,  74,  76  and  77%. 
These  percentages  refer  to  the  percentage  of  sodium 
oxide  (Na^O)  in  100  parts  of  pure  caustic  soda  formed 
by  the  combination  of  77j^  parts  of  sodium  oxide  and 
22J/2  parts  of  water,  77l/2%  being  chemically  pure  caustic 
soda.  There  are  generally  impurities  present  in  com- 
mercial caustic  soda.  These  consist  of  sodium  carbonate, 
sodium  chloride  or  common  salt  and  sometimes  lime.  It 
is  manufactured  by  treating  sodium  carbonate  in  an  iron 
vessel  with  calcium  hydroxide  or  slaked  lime,  or  by  elec- 
trolysis of  common  salt.  The  latter  process  has  yet  been 
unable  to  compete  with  the  former  in  price.  Formerly 
all  the  caustic  soda  used  in  soap  making  was  imported, 
and  it  was  only  through  the  American  manufacturer 
using  a  similar  container  to  that  used  by  foreign  manu- 
facturers that  they  were  able  to  introduce  their  product. 
This  prejudice  has  now  been  entirely  overcome  and  most 
of  the  caustic  soda  used  in  this  country  is  manufactured 
here. 

CAUSTIC    POTASH. 

The  output  of  the  salts  containing  potassium  is  con- 
trolled almost  entirely  by  Germany.  Formerly  the  chief 
source  of  supply  of  potassium  compounds  was  from  the 
burned  ashes  of  plants,  but  about  fifty  years  ago  the  in- 
exhaustible salt  mines  of  Stassfurt,  Germany,  were  dis- 

26 


RAW  MATERIALS 

covered.  The  salt  there  mined  contains,  besides  the 
chlorides  and  sulphates  of  sodium,  magnesium,  calcium 
and  other  salts,  considerable  quantities  of  potassium 
chloride,  and  the  Stassfurt  mines  at  present  are  prac- 
tically the  entire  source  of  all  potassium  compounds,  in 
spite  of  the  fact  that  other  localities  have  been  sought 
to  produce  these  compounds  on  a  commercial  basis,  espe- 
cially by  the  United  States  government. 

After  separating  the  potassium  chloride  from  the  mag- 
nesium chloride  and  other  substances  found  in  Stassfurt 
salts  the  methods  of  manufacture  of  caustic  potash  are 
identical  to  those  of  caustic  soda.  In  this  case,  however, 
domestic  electrolytic  caustic  potash  may  be  purchased 
cheaper  than  the  imported  product  and  it  gives  results 
equal  to  those  obtained  by  the  use  of  the  imported  article, 
opinions  to  the  contrary  among  soap  makers  being  many. 
Most  of  the  caustic  potash  in  the  United  States  is  manu- 
factured at  Niagara  Falls  by  the  Niagara  Alkali  Co., 
and  the  Hooker  Electrochemical  Co.,  chlorine  being  ob- 
tained as  a  by-product.  The  latter  concern  employs  the 
Townsend  Cell,  for  the  manufacture  of  electrolytic  pot- 
ash, and  are  said  to  have  a  capacity  for  making  64  tons 
of  alkali  daily. 

Since  the  molecular  weight  of  caustic  potash  (56)  is 
greater  than  that  of  caustic  soda  (40)  more  potash  is 
required  to  saponify  a  pound  of  fat.  The  resulting  potash 
soap  is  correspondingly  heavier  than  a  soda  soap.  When 
salt  is  added  to  a  potassium  soap  double  decomposition 
occurs,  the  potassium  soap  being  transformed  to  a  so- 
dium soap  and  the  potassium  uniting  with  the  chlorine  to 
form  potassium  chloride.  This  was  one  of  the  earliest 
methods  of  making  a  hard  soap,  especially  in  Germany, 
where  potash  was  derived  from  leeching  ashes  of  burned 
wood  and  plants. 

27 


SOAP-MAKING    MANUAL 

SODIUM    CARBONATE     (SODA    ASH). 

While  carbonate  of  soda  is  widely  distributed  in  na- 
ture the  source  of  supply  is  entirely  dependent  upon  the 
manufactured  product.  Its  uses  are  many,  but  it  is  espe- 
cially important  to  the  soap  industry  in  the  so  called  car- 
bonate saponification  of  free  fatty  acids,  as  a  constituent 
of  soap  powders,  in  the  neutralization  of  glycerine  lyes 
and  as  a  filler  for  laundry  soaps. 

The  old  French  Le  Blanc  soda  process,  which  consists 
in  treating  common  salt  with  sulphuric  acid  and  reducing 
the  sodium  sulphate  (salt  cake)  thus  formed  with  car- 
bon in  the  form  of  charcoal  or  coke  to  sodium  sulphide, 
which  when  treated  with  calcium  carbonate  yields  a  mix- 
ture of  calcium  sulphide  and  sodium  carbonate  (black  ash) 
from  which  the  carbonate  is  dissolved  by  water,  has  been 
replaced  by  the  more  recent  Solvay  ammonia  soda  process. 
Even  though  there  is  a  considerable  loss  of  salt  and  the  by- 
product calcium  chloride  produced  by  this  process  is  only 
partially  used  up  as  a  drying  agent,  and  for  refrigerating 
purposes,  the  Le  Blanc  process  cannot  compete  with  the 
Solvay  process,  so  that  the  time  is  not  far  distant  when 
the  former  will  be  considered  a  chemical  curiosity.  In 
the  Solvay  method  of  manufacture  sodium  chloride  (com- 
mon salt)  and  ammonium  bicarbonate  are  mixed  in  so- 
lution. Double  decomposition  occurs  with  the  formation 
of  ammonium  chloride  and  sodium  bicarbonate.  The  lat- 
ter salt  is  comparatively  difficultly  soluble  in  water  and 
crystallizes  out,  the  ammonium  chloride  remaining  in  so- 
lution. When  the  sodium  bicarbonate  is  heated  it  yields 
sodium  carbonate,  carbon  dioxide  and  water ;  the  car- 
bon dioxide  is  passed  into  ammonia  which  is  set  free  from 
the  ammonium  chloride  obtained  as  above  by  treatment 
with  lime  (calcium  oxide)  calcium  chloride  being  the  by- 
product. 

28 


RAW  MATERIALS 

Sal  soda  or  washing  soda  is  obtained  by  recrystallizing 
a  solution  of  soda  ash  in  water.  Large  crystals  of  sal 
soda  containing  but  37%  sodium  carbonate  are  formed. 

POTASSIUM    CARBONATE. 

Potassium  carbonate  is  not  extensively  used  in  the 
manufacture  of  soap.  It  may  be  used  in  the  forming  of 
soft  soaps  by  uniting  it  with  free  fatly  acids.  The  meth- 
ods of  manufacture  are  the  same  as  fcr  sodium  carbonate, 
although  a  much  larger  quantity  of  potassium  carbonate 
than  carbonate  of  soda  is  obtained  from  burned  plant 
ashes.  Purified  potassium  carbonate  is  known  as  pearl  ash. 

ADDITIONAL    MATERIAL    USED   IN    SOAP    MAKING. 

Water  is  indispensable  to  the  soap  manufacturer.  In  the 
soap  factory  hard  water  is  often  the  cause  of  much  trouble. 
Water,  which  is  the  best  solvent  known,  in  passing  through 
.the  crevices  of  rocks  dissolves  some  of  The  constituents 
of  these,  and  the  water  is  known  as  hard.  This  hard- 
ness is  of  two  kinds,  temporary  and  permanent.  Tem- 
porarily hard  water  is  formed  by  water,  which  contains 
carbonic  acid,  dissolving  a  portion  of  calcium  carbonate 
or  carbonate  of  lime.  Upon  boiling,  the  carbonic  acid  is 
driven  from  the  water  and  the  carbonate,  being  insoluble 
in  carbon  dioxide  free  water,  is  deposited.  This  is  the 
cause  of  boiler  scale,  and  to  check  this  a  small  amount  of 
sal  ammoniac  may  be  added  to  the  water,  which  con- 
verts the  carbonate  into  soluble  calcium  chloride  and 
volatile  ammonium  carbonate.  Permanent  hardness  is 
caused  by  calcium  sulphate  which  is  soluble  in  400  parts 
of  water  and  cannot  be  removed  by  boiling. 

The  presence  of  these  salts  in  water  form  insoluble  lime 
soaps  which  act  as  inert  bodies  as  far  as  their  value  for 
the  common  use  of  soap  is  concerned.  Where  the  per- 
centage of  lime  in  water  is  large  this  should  be  removed. 

29 


SOAP-MAKING    MANUAL 

A  method  generally  used  is  to  add  about  5%  of  20°  B. 
sodium  silicate  to  the  hard  water.  This  precipitates  the 
lime  and  the  water  is  then  sufficiently  pure  to  use. 

Salt,  known  as  sodium  chloride,  is  used  to  a  large  ex- 
tent in  soap  making  for  "salting  out"  the  soap  during 
saponification,  as  well  as  graining  soaps.  Soap  ordinarily 
soluble  in  water  is  insoluble  in  a  salt  solution,  use  pf 
which  is  made  by  adding  salt  to  the  soap  which  goes 
into  solution  and  throws  any  soap  dissolved  in  the  lyes 
out  of  solution.  Salt  may  contain  magnesium  and  cal- 
cium chlorides,  which  of  course  are  undesirable  in  large 
amounts.  The  products  on  the  market,  however,  are 
satisfactory,  thus  no  detail  is  necessary. 

Filling  materials  used  are  sodium  silicate,  or  water 
glass,  talc,  silex,  pumice,  starch,  borax,  tripoli,  etc. 

Besides  these  other  materials  are  used  in  the  refining 
of  the  oils  and  fats,  and  glycerine  recovery,  such  as 
Fuller's  earth,  bichromates  of  soda  or  potash,  sulphate  of 
alumina,  sulphuric  and  hydrochloric  acids  and  alcohol. 

A  lengthy  description  of  these  substances  is  not  given, 
as  their  modes  of  use  are  detailed  elsewhere. 


30 


CHAPTER   II 
Construction  and  Equipment  of  a  Soap  Plant 

No  fixed  plan  for  the  construction  and  equipment 
of  a  soap  plant  can  be  given.  The  specifications  for  a 
soap  factory  to  be  erected  or  remodeled  must  suit  the 
particular  cases.  Very  often  a  building  which  was  con- 
structed for  a  purpose  other  than  soap  manufacture  must 
be  adapted  for  the  production  of  soap.  In  either  case 
it  is  a  question  of  engineering  and  architecture,  together 
with  the  knowledge  obtained  in  practice  and  the  final  de- 
cision as  to  the  arrangement  is  best  solved  by  a  confer- 
ence with  those  skilled  in  each  of  these  branches. 

An  ideal  soap  plant  is  one  in  which  the  process  of  soap 
making,  from  the  melting  out  of  the  stock  to  the  packing 
and  shipping  of  the  finished  product,  moves  downward 
from  floor  to  floor,  since  by  this  method  it  is  possible  to 
utilize  gravitation  rather  than  pumping  liquid  fats  and 
fluid  soaps.  Convenience  and  economy  are  obtained  by 
such  an  arrangement. 

The  various  machinery  and  other  equipment  for  soap 
manufacture  are  well  known  to  those  connected  with  this 
industry.  It  varies,  of  course,  depending  upon  the  kind 
of  soap  to  be  manufactured,  and  full  descriptions  of  the 
necessary  machinery  are  best  given  in  the  catalogs  issued 
by  the  manufacturers  of  such  equipment,  who  in  this 
country  are  most  reliable. 

To  know  just  what  equipment  is  necessary  can  very 
easily  be  described  by  a  brief  outline  of  the  process  vari- 
ous soaps  undergo  to  produce  the  finished  article.  After 
the  saponification  has  taken  place  in  the  soap  kettle  the 
molten  stJ^p  is  run  directly  into  the  soap  frames, 

31 


SOAP-MAKING    MANUAL 

which  consist  of  an  oblong  compartment,  holding  any- 
where from  400  to  1,200  pounds,  with  removable  steel 
sides  and  mounted  upon  trucks,  in  which  it  solidifies.  In 
most  cases  it  is  advisable  to  first  run  the  soap  into  a 
crutcher  or  mixer  which  produces  a  more  homogeneous 
mass  than  if  this  operation  is  omitted.  Color  and  per- 
fume may  also  be  added  at  this  point,  although  when  a 
better  grade  of  perfume  is  added  it  must  be  remembered 
that  there  is  considerable  loss  due  to  volatilization  of 
same.  When  a  drying  machine  is  employed  the  molten 
soap  is  run  directly  upon  the  rollers  of  this  machine, 
later  adding  about  1.0%  zinc  oxide  to  the  soap  from 
which  it  passes  continuously  through  the  drying  chamber 
and  is  emitted  in  chip  form  ready  for  milling.  After 
the  soap  has  been  framed,  it  is  allowed  to  cool  and 
solidify,  which  takes  several  days,  and  then  the  sides  of 
the  frame  are  stripped  off.  The  large  solid  cake  is  cut  with 
wires  by  hand  or  by  a  slabber  into  slabs  of  any  desired 
size.  These  slabs  are  further  divided  into  smaller  di- 
visions by  the  cutting  table.  In  non-milled  soaps  (laun- 
dry soaps,  floating  soaps,  etc.),  these  are  pressed  at  this 
stage,  usually  by  automatic  presses,  after  a  thin  hard 
film  has  been  formed  over  the  cake  by  allowing  it  to  dry 
slightly.  In  making  these  soaps  they  are  not  touched  by 
hand  at  any  time  during  the  operation,  the  pressing, 
wrapping  and  packing  all  being  done  by  machinery.  For 
a  milled  soap  the  large  slabs  are  cut  into  narrow  oblong 
shapes  by  means  of  the  cutting  table  to  readily  pass  into 
the  feeder  of  the  chipper,  the  chips  being  spread  upon 
trays  and  dried  in  a  dry  house  until  the  moisture  content 
is  approximately  15%. 

The  process  of  milling  is  accomplished  by  passing  the 
dried  soap  chips  through  a  soap  mill,  which  is  a  machine 
consisting  of  usually  three  or  four  contiguous,  smooth, 

32 


CONSTRUCTION  AND  EQUIPMENT 

granite  rollers  operated  by  a  system  of  gears  and  set 
far  enough  apart  to  allow  the  soap  to  pass  from  a  hopper 
to  the  first  roller,  from  which  it  is  constantly  conveyed 
to  each  succeeding  roller  as  a  thin  film,  and  finally 
scraped  from  the  last  roller  to  fall  into  the  milling  box 
in  thin  ribbon  form.  These  mills  are  often  operated  in 
tandem,  which  necessitates  less  handling  of  soap  by  the 
operator.  The  object  of  milling  is  to  give  the  soap  a 
glossy,  smooth  finish  and  to  blend  it  into  a  homogeneous 
mass.  The  perfume,  color,  medication  or  any  other  ma- 
terial desired  are  added  to  the  dried  soap  chips  prior  to 
milling.  Some  manufacturers  use  an  amalgamator  to 
distribute  these  uniformly  through  the  soap,  which  elimi- 
nates at  least  one  milling.  When  a  white  soap  is  being 
put  through  the  mill,  it  is  advisable  to  add  from 
0.5%  to  \%  of  a  good,  fine  quality  of  zinc  oxide  to  the 
soap,  if  this  substance  has  not  been  previously  added. 
This  serves  to  remove  the  yellowish  cast  and  any  trans- 
lucency  occasioned  by  plodding.  Too  great  a  quantity 
of  this  compound  added,  later  exhibits  itself  by  imparting 
to  the  soap  a  dead  white  appearance.  Inasmuch  as  the 
milling  process  is  one  upon  which  the  appearance  of  a 
finished  cake  of  toilet  soap  largely  depends,  it  should  be 
carefully  done.  The  number  of  times  a  soap  should  be 
milled  depends  upon  the  character  of  a  soap  being  worked. 
It  should  of  course  be  the  object  to  mill  with  as  high  a 
percentage  of  moisture  as  possible.  Should  the  soap  be- 
come too  dry  it  is  advisable  to  add  water  directly,  rather 
than  wet  soap,  since  water  can  more  easily  be  distributed 
through  the  mass.  As  a  general  statement  it  may  be  said 
it  is  better  policy  to  overmill  a  soap,  rather  than  not  mill 
it  often  enough. 

After  the  soap  has  been  thoroughly  milled  it  is  ready 
for  plodding.    A  plodder  is  so  constructed  as  to  take  the 

33 


SOAP-MAKING    MANUAL 

soap  ribbons  fed  into  the  hopper  by  means  of  a  worm  screw 
and  continuously  force  it  under  great  pressure  through  a 
jacketed  cylinder  through  which  cold  water  circulates  in 
the  rear  to  compensate  the  heat  produced  by  friction  and 
hot  water  at  the  front,  to  soften  and  polish  the  soap  which 
passes  out  in  solid  form  in  bars  of  any  shape  and  size 
depending  upon  the  form  of  the  shaping  plate  through 
which  it  is  emitted.  The  bars  run  upon  a  roller  board, 
are  cut  into  the  required  length  by  a  special  cake  cutting 
table,  allowed  to  dry  slightly  and  pressed  either  auto- 
matically or  by  a  foot  power  press  in  any  suitable  soap  die. 
The  finished  cake  is  then  ready  for  wrapping  and  after  due 
time  in  stock  reaches  the  consumer. 

Besides  the  various  apparatus  mentioned  above  there  are 
many  other  parts  for  the  full  equipment  of  a  modern  soap 
plant,  such  as  remelters,  pumps,  mixers,  special  tanks, 
power  equipment,  etc.  As  has  been  stated,  however,  prac- 
tical experience  will  aid  in  judging  the  practicability  as  to 
installation  of  these.  The  various  methods  of  powdering 
soap  are,  however,  not  generally  known.  Where  a  coarse 
powder  is  to  be  produced,  such  as  is  used  for  common 
washing  powders,  no  great  difficulty  is  experienced  with 
the  well  known  Blanchard  mill.  In  grinding  soap  to  an 
impalpable  powder  the  difficulties  increase.  The  methods 
adapted  in  pulverizing  soaps  are  by  means  of  disinte- 
grators, pebble  mills  and  chaser  mills.  The  disintegrator 
grinds  by  the  principle  of  attrition,  that  is,  the  material  is 
reduced  by  the  particles  being  caused  to  beat  against  each 
other  at  great  velocity;  a  pebble  mill  crushes  the  sub- 
stance by  rubbing  it  between  hard  pebbles  in  a  slowly  re- 
volving cylinder;  the  chaser  mill  first  grinds  the  material 
and  then  floats  it  as  a  very  fine  powder  above  a  curb  of 
fixed  height.  The  last  method  is  particularly  adapted  for 
the  finest  of  powder  (140  mesh  and  over). 

34 


CHAPTER    III 

Classification   of  Soap-Making   Methods. 

In  the  saponification  of  fats  and  oils  to  form  soap 
through  the  agency  of  caustic  alkalis,  as  has  been  stated, 
the  sodium  or  potassium  salts  of  the  mixed  fatty  acids  are 
formed.  Sodium  soaps  are  usually  termed  hard  soaps,  and 
potassium  soaps  soft.  There  are,  however,  a  great  many 
varieties  of  soaps  the  appearance  and  properties  of  which 
depend  upon  their  method  of  manufacture  and  the  oils  or 
fats  used  therein. 

The  various  methods  adopted  in  soap  making  may  be 
thus  classified: 

1.  Boiling  the   fats   and   oils  in   open   kettles   by  open 
steam  with  indefinite  quantities  of  caustic  alkali  solutions 
until  the  finished  soap  is  obtained;  ordinarily  named  full 
boiled  soaps.     These  may  be  sub-divided  into    (a)    hard 
soaps  with  sodium  hydrate  as  a  base,  in  which  the  glycerine 
is   recovered   from  the  spent  lyes;    (b)    hard  soaps  with 
soda  as   a   base,   in   which   the   glycerine    remains   in   the 
soap,   e.  g.,  marine  cocoanut  oil  soaps;    (c)    soft  potash 
soaps,  in  which  the  glycerine  is  retained  by  the  soap. 

2.  Combining  the  required  amount  of  lye  for  complete 
saponification  of  a  fat  therewith,  heating  slightly  with  dry 
heat  and  then  allowing  the  saponification  to  complete  itself. 
This  is  known  as  the  cold  process. 

3.  Utilizing  the  fatty  acid,  instead  of  the  neutral  fat, 
and  combining  it  directly  with  caustic  alkali  or  carbonate, 
which  is  incorrectly  termed  carbonate  saponification,  since 
it  is  merely  neutralizing  the  free  fatty  acid  and  thus  is 
not  a  saponification  in  the  true  sense  of  the  word.     No 
glycerine   is    directly   obtained   by   this   method,   as   it   is 

35 


SOAP-MAKING    MANUAL 

usually  previously  removed  in  the  clearage  of  the  fat  by 
cither  the  Twitchell  or  autoclave  saponification  method. 

In  the  methods  thus  outlined  the  one  most  generally 
employed  is  the  full  boiled  process  to  form  a  sodium  soap. 
This  method  of  making  soap  requires  close  attention  and 
a  knowledge  which  can  only  be  obtained  by  constant  prac- 
tice. The  stock,  strength  of  lyes,  heat,  amount  of  salt  or 
brine  added,  time  of  settling,  etc.,  are  all  influencing 
factors. 

The  principles  involved  in  this  process  are  briefly  these: 

The  fat  is  partly  saponified  with  weak  lyes  (usually 
those  obtained  from  a  previous  boiling  in  the  strengthening 
change  are  used),  and  salt  is  added  to  grain  the  soap.  The 
mass  is  then  allowed  to  settle  into  two  layers.  The  upper 
layer  is  partly  saponified  fat;  the  lower  layer,  or  spent  lye, 
is  a  solution  of  salt,  glycerine,  and  contains  any  albuminous 
matter  or  any  other  impurity  contained  in  the  fat.  This 
is  known  as  the  killing  or  glycerine  change.  Strong  lyes 
are  now  added  and  the  fat  entirely  saponified,  which  is 
termed  the  strengthening  change.  The  mass  is  then  al- 
lowed to  settle  and  the  fluid  soap  run  of!  above  the  "nigre." 
This  operation  is  called  the  finish  or  finishing  change. 

The  method  may  be  more  fully  illustrated  by  a  concrete 
example  of  the  method  of  manufacture  of  a  tallow  base: 

Charge — 

Tallow    88  per  cent. 

Cocoanut  oil 10  per  cent. 

Rosin  w.  w 2  per  cent. 

Amount   charge 10  tons 

About  five  tons  of  tallow  and  one  ton  of  cocoanut  oil 
are  pumped  or  run  into  the  soap  kettle  and  brought  to  a 
boil  with  wet  steam  until  it  briskly  comes  through  the  hot 
fat.  The  caustic  soda  (strengthening  lyes  from  former 

36 


SOAP-MAKING     METHODS 

boilings  may  be  used  here)  is  gradually  added  by  the  dis- 
tributing pipe,  any  tendency  to  thicken  being  checked  by 
the  introduction  of  small  quantities  of  brine  ("salt  pickle"). 
If  the  lye  is  added  too  rapidly  the  soap  assumes  a  granular 
appearance,  indicating  that  the  addition  of  same  must  be 
discontinued.  Water  should  then  be  added  and  the  mass 
boiled  through  until  it  again  closes.  When  the  addition 
of  the  proper  amount  of  caustic  soda  is  nearing  its  com- 
pletion the  soap  gradually  thins.  The  steam  is  now  cut 
down  to  about  one  turn  of  the  valve,  and  brine  is  rapidly 
added  or  salt  shoveled  in.  In  ten  to  fifteen  minutes  the 
steam  again  breaks  through  and,  from  the  appearance  of 
the  soap,  it  can  be  seen  whether  sufficient  brine  has  been 
added.  A  sample  taken  out  by  means  of  a  long  wooden 
paddle  should  show  the  soap  in  fine  grains  with  the  lyes 
running  from  it  clear.  The  steam  is  then  shut  off  and  the 
soap  allowed  to  settle  from  one  and  one-half  to  two  hours. 
In  all  settlings  the  longer  time  this  operation  is  permitted 
to  continue,  the  better  will  the  subsequent  operations 
proceed. 

The  mixture  now  consists  of  a  partly  saponified  layer 
of  fat  above  the  spent  lyes.  The  lyes  are  drawn  off  until 
soap  makes  its  appearance  at  the  exit  pipe.  The  valve  is 
then  closed  and  the  soap  blown  back  into  the  kettle  by 
steam.  The  lyes  thus  obtained  are  known  as  spent  lyes, 
from  which  the  glycerine  is  recovered.  They  should  show 
an  alkalinity  of  approximately  0.5  per  cent,  if  the  operation 
is  carefully  carried  out. 

The  remaining  tallow  is  now  added  and  the  above  oper- 
ations repeated. 

After  the  spent  lyes  have  been  drawn  off,  the  soap  is 
closed  with  water  and  the  proper  percentage  of  rosin  soap 
previously  formed,  or  rosin  itself  is  added  to  the  mass  in 
the  kettle.  More  lye  is  then  allowed  to  flow  in  until  the 

37 


SOAP-MAKING    MANUAL 

mixture  is  up  to  "strength."  This  is  usually  tested  by  the 
"bite"  on  the  tongue  of  a  small  cooled  sample.  After  boil 
ing  until  the  steam  comes  through,  the  mass  is  grained  with 
salt  as  before  and  allowed  to  settle  one  and  one-half  to 
three  hours.  These  lyes,  known  as  strengthening  lyes 
are  run  to  storage  to  be  used  subsequently  with  fresh  fat 
to  take  up  the  caustic  soda  contained  therein. 

The  soap  is  now  ready  for  finishing  and  is  first  boiled 
through  and  tried  for  strength.  A  drop  of  phenolphthalein 
(1  per  cent,  phenolphthalein  in  98  per  cent,  alcohol)  is  al- 
lowed to  drop  on  the  molten  soap  taken  up  on  a  trowel. 
The  red  color  should  be  instantly  produced  and  develop  to 
a  full  deep  crimson  in  a  few  seconds,  or  more  lye  must  be 
added  until  this  condition  is  realized.  Should  it  flash  a 
deep  crimson  immediately  it  is  on  the  strong  side.  This 
cannot  be  conveniently  remedied;  it  can  only  serve  as  a 
guide  for  the  next  boil,  but  in  any  case  it  is  not  of  any 
serious  consequence,  unless  it  is  too  strong. 

With  the  steam  on,  the  soap  is  now  examined  with  a 
trowel  which  must  be  thoroughly  heated  by  working  it 
about  under  the  surface  of  the  hot  soap.  The  appearance 
of  the  soap  as  it  runs  from  the  face  of  the  trowel  indicates 
its  condition.  It  is  not  possible  to  absolutely  describe  the 
effect,  which  can  only  be  properly  judged  by  practice,  yet 
the  following  points  may  serve  as  a  guide.  The  indications 
to  be  noticed  are  the  shape  and  size  of  the  flakes  of  soap 
as  the  sample  on  the  trowel  breaks  up  and  runs  from  the 
hot  iron  surface,  when  the  latter  is  turned  in  a  vertical 
position,  as  well  as  the  condition  of  the  iron  surface  from 
which  the  soap  flakes  have  fallen.  A  closed  soap  will  run 
slowly  into  a  homogeneous  sheet,  leaving  the  trowel's  sur- 
face covered  with  a  thin  layer  of  transparent  soap ;  a 
grained  mass  will  run  rapidly  down  in  tiny  grains,  about 
one-half  an  inch  in  diameter  or  less,  leaving  the  hot  trowel 

38 


SOAP-MAKING     METHODS 

absolutely  dry.  The  object  of  the  finish  is  to  separate  the 
soaps  of  the  lower  fatty  acids  from  those  of  the  higher,  and 
both  from  excess  of  liquid.  A  point  midway  between 
''open"  and  "closed"  is  required  to  arrive  at  this  point. 

Having  arrived  at  the  above  condition,  the  soap  is  al- 
lowed to  settle  anywhere  from  one  to  three  days  and  then 
run  off  through  the  skimmer  pipes  to  the  nigre  and  framed 
or  pumped  to  the  tank  feeding  the  drying  machine. 

The  stock  thus  obtained  should  be  fairly  white,  depend- 
ing upon  the  grade  of  tallow  used  and  slightly  alkaline  to 
an  alcoholic  phenolphthalein  solution.  If  removed  at  ex- 
actly the  neutral  point  or  with  a  content  of  free  fat  the 
soap  will  sooner  or  later  develop  rancidity.  The  soap  thus 
obtained  is  an  ordinary  tallow  base,  and  the  one  by  far 
greatest  used  in  the  manufacture  of  toilet  soaps.  The  per- 
centage of  cocoanut  oil  indicated  is  not  fixed  and  may 
readily  be  varied,  while  in  fine  toilet  soap  the  rosin  is 
usually  eliminated. 

In  the  manufacture  of  full  boiled  soda  soaps  in  which  no 
glycerine  is  obtained  as  a  by-product,  it  being  retained  in 
the  soap  itself,  the  soap  formed  is  known  as  a  "run"  soap. 
The  process  is  used  most  extensively  in  the  manufacture 
of  marine  soaps  by  which  the  method  may  be  best  illus- 
trated. This  soap  is  known  as  marine  soap  because  of  its 
property  of  readily  forming  a  lather  with  salt  water  and 
is  mostly  consumed  aboard  vessels. 

Marine  soaps  are  manufactured  by  first  placing  in  the 
kettle  a  calculated  amount  of  lye  of  25  deg.  to  35  deg.  B., 
depending  upon  the  amount  of  moisture  desired  in  the  fin- 
ished soaps,  plus  a  slight  excess  required  to  saponify  a 
known  weight  of  cocoanut  oil.  With  open  steam  on,  the 
cocoanut  oil  is  then  gradually  added,  care  being  taken  that 
the  soap  does  not  froth  over.  Saponification  takes  place 
readily  and  when  the  oil  is  entirely  saponified  the  finished 

39 


SOAP-MAKING     MANUAL 

soap  is  put  through  the  process  known  as  running.  This 
consists  in  constantly  pumping  the  mass  from  the  skimmer 
pipe  back  into  the  top  of  the  kettle,  the  object  being  to 
prevent  any  settling  of  the  nigre  or  lye  from  the  soap,  as 
well  as  producing  a  homogeneous  mass.  It  is  customary 
to  begin  the  saponification  in  the  morning,  which  should  be 
completed  by  noon.  The  soap  is  then  run  for  about  three 
hours  and  framed  the  next  morning.  After  having  re- 
mained in  the  frame  the  time  required  to  solidify  and  cool, 
the  soap  is  slabbed  and  cut  into  cakes.  This  process  is 
difficult  to  carry  out  properly,  and  one  not  greatly  em- 
ployed, although  large  quantities  of  marine  soap  are  pur- 
chased by  the  government  for  use  in  the  navy  and  must 
fulfill  certain  specifications  required  by  the  purchasing 
department. 

In  making  potash  soaps  it  is  practically  impossible  to  ob- 
tain any  glycerine  directly  because  of  the  pasty  consistency 
of  the  soap,  and  no  graining  is  possible  because  the  addi- 
tion of  salt  to  a  soft  soap,  as  already  explained,  would  form 
a  soda  soap.  Large  quantities  of  soft  soaps  are  required  for 
the  textile  industries  who  desire  mostly  a  strong  potash 
soap,  and  the  large  number  of  automobiles  in  use  at  the 
present  time  has  opened  a  field  for  the  use  of  a  soft  soap 
for  washing  these.  A  soap  for  this  purpose  must  be  neu- 
tral so  as  not  to  affect  the  varnish  or  paint  of  automobiles. 

A  suitable  soap  for  textile  purposes  may  be  made  as 
follows : 

Red  oil   80     parts 

House  grease    20     parts 

Caustic  soda  lye,  36  degs.  B .  . . .     3     parts 

Carbonate  of  potash $y2  parts 

Caustic  potash    23%  parts 

Olive  oil,  corn  oil,  soya  bean  oil,  olive  oil  foots  or  cot- 
40 


SOAP-MAKING     METHODS 

tonseed  oil  may  replace  any  of  the  above  oils.     A  large 
quantity  of  cottonseed  oil  will  cause  the  soap  to  fig. 

To  carry  out  the  process,  the  caustic  potash  and  car- 
bonate of  potash  are  dissolved  and  p'laced  in  the  kettle 
together  with  the  soda  lye,  and  the  oils  added.  This  is 
most  satisfactorily  accomplished  by  being  finished  the  day 
before  the  boiling  is  begun.  The  next  day  the  boiling  is 
begun  and  water  added  to  bring  the  soap  up  to  the  desireu 
percentage  of  fatty  acid,  due  allowance  being  made  for  the 
water  formed  by  the  condensation  of  the  open  steam  in 
boiling.  Care  must  be  taken  that  the  soap  in  the  kettle 
does  not  swell  and  run  over  during  the  saponification. 
A  good  procedure  is  to  use  open  steam  for  a  period  of 
about  two  hours,  then  close  the  valve  and  allow  the  sapon- 
ification to  continue  without  boiling,  and  repeat  this  until 
it  is  entirely  saponified.  After  the  saponification  has  been 
completed  the  soap  is  briskly  boiled  all  day  and  the  proper 
corrections  made ;  that  is,  if  too  alkaline,  more  oil  is  added, 
and  if  free  fat  is  present,  more  potash.  About  2  per  cent, 
carbonate  of  potash  is  the  proper  amount  for  a  soap  con- 
taining 50  per  cent,  fatty  acid.  The  soap  is  sampled  by 
allowing  it  to  drop  on  a  clean,  cold  glass  surface.  In  so 
doing,  the  soap  should  not  slide  or  slip  over  the  glass  sur- 
face when  pressed  thereon,  but  should  adhere  to  the  glass, 
or  it  is  too  alkaline.  A  sample  worked  between  the  fingers 
showing  too  much  stringiness  should  have  more  strong 
potash  and  oil  added.  A  sample  taken  out  in  a  pail  and 
allowed  to  cool  over  night  will  serve  as  a  guide  as  to  the 
body  of  the  soap  in  the  kettle.  When  the  soap  has  thus 
been  properly  finished  it  is  run  into  barrels. 

For  an  automobile  soap  the  following  is  a  good  working 
formula : 

Corn    oil....: l,000parts 

Potash  lye,  31l/2  degs.  B 697  parts 

41 


SOAP-MAKING    MANUAL 

Proceed  as  in  the  directions  just  given  for  textile  soap 
in  placing  charge  in  the  kettle.  When  the  kettle  is  boiling 
up  well,  shut  off  the  steam  and  the  saponification  will  com- 
plete itself.  The  soap  may  be  run  into  the  barrels  the 
next  day. 

A  heavy  soap  with  a  smaller  percentage  of  fat  may  be 
made  as  follows: 

Corn   oil l.OOOparts 

Potash  lye,  24^  degs.  B 900  parts 

Boil  until  the  soap  bunches,  and  shovel  the  finished  soap 
into  barrels.  Upon  standing  it  will  clear  up.  By  the  addi- 
tion of  more  water  the  yield  of  soap  per  pound  of  oil  may 
be  run  up  to  300  per  cent. 

After  soft  soaps  have  been  allowed  to  stand  for  some 
time  the  phenomenon  known  as  "figging"  often  occurs. 
This  term  is  applied  to  a  crystalline-like  formation,  caus- 
ing spots  of  a  star-like  shape  throughout  the  soap. 
This  is  undoubtedly  due  to  the  stearine  content  of  the  soap 
crystallizing  out  as  it  cools,  and  forming  these  peculiarly- 
shaped  spots.  It  more  generally  occurs  in  the  winter  and 
may  be  produced  artificially  by  adding  a  small  quantity  ot 
soda  to  the  potash  lye  before  saponification. 

The  oils  usually  employed  in  the  manufacture  of  potash 
soaps  are  cottonseed  oil,  corn  oil,  soya  bean  oil,  olive  oil 
foots,  red  oil,  cocoanut  oil,  grease  and  the  various  train 
oils.  The  usual  percentage  yield  is  from  225  per  cent,  to 
300  per  cent.,  based  upon  the  weight  of  oil  used.  In  cal- 
culating the  weight  of  a  soft  soap  it  is  to  be  remembered 
that  since  potassium  has  a  higher  molecular  weight  (56) 
than  sodium  (40),  the  corresponding  soap  formed  is  that 
much  greater  in  weight  when  compared  with  a  sodium 
soap.  Rosin  may  be  added  to  soft  soaps  as  a  cheapening 
agent. 

42 


SOAP-MAKING     METHODS 

COLD  PROCESS. 

The  cold  process  for  manufacturing  soap  is  the  simplest 
method  of  soap  making,  and  the  equipment  required  is  small 
when  compared  to  the  other  methods.  All  the  more  expensive 
equipment  that  is  necessary  is  a  crutcher,  a  tank  to  hold  the 
lye,  frames,  a  slabber  or  cutting  table,  and  a  press.  Yet, 
in  spite  of  the  simplicity  of  thus  making  soap,  the  disad- 
vantages are  numerous  for  the  production  of  a  good  piece 
of  soap.  The  greatest  difficulty  is  to  obtain  a  thorough 
combination  of  oil  or  fat  and  lye  so  that  there  will  not  be 
an  excess  of  one  or  the  other  in  the  finished  soap.  At  its 
best  there  is  either  a  considerable  excess  of  free  fat  which 
later  exhibits  itself  in  producing  rancidity  or  uncombined 
caustic,  which  produces  an  unpleasant  effect  on  the  skin 
when  the  soap  is  consumed  for  washing.  The  latter  ob- 
jection, of  course,  can  only  be  applied  to  toilet  soaps. 

Cocoanut  oil  is  used  very  largely  in  the  manufacture  of 
cold-made  soaps  as  it  is  well  adapted  for  this  purpose,  al- 
though it  is  by  no  means  true  that  other  oils  may'not  be 
employed.  Since  by  this  process  of  manufacture  no  im- 
purity contained  in  the  fat  or  oil  is  removed  in  the  making 
of  the  soap,  it  is  necessary  that  in  order  to  obtain  a  fine 
finished  product,  any  impurity  contained  in  these  may  be 
removed  if  present,  or  that  the  fats  be  as  pure  as  can  be 
obtained.  If  inedible  tallow  is  used  for  cold-made  soap, 
it  is  advisable  to  bleach  it  by  the  Fuller's  Earth  Process. 

The  carrying  out  of  this  method  is  best  illustrated  by 
an  example  of  a  cold-made  cocoanut  oil  soap. 

Charge : 

Cochin  cocoanut  oil 846  parts 

Lye  (soda),  35  degs.  B 470  parts 

Water    24  parts 

43 


SOAP-MAKING     MANUAL 

The  oil  is  run  into  the  crutcher  and  the  temperature  of 
the  oil  raised  to  100  degs.  F.  by  dry  steam.  The  lye  and 
water  are  at  room  temperature.  After  all  the  oil  is  in  the 
crutcher,  the  lye  and  water  are  slowly  added  to  prevent 
any  graining  of  the  soap.  Toward  the  end  the  lye  may  be 
added  more  rapidly.  When  all  the  lye  is  in,  the  mass  is 
crutched  for  about  three  hours,  or  until  upon  stopping 
the  crutcher  a  finger  drawn  over  the  surface  of  the  soap 
leaves  an  impression.  If  this  condition  is  not  realized, 
the  soap  must  be  mixed  until  such  is  the  case.  Having  ar- 
rived at  this  point,  the  mixture  is  dropped  into  a  frame 
which  should  remain  uncovered.  The  heat  produced  by  the 
further  spontaneous  saponification  will  cause  the  soap  to 
rise  in  the  middle  of  the  frame.  After  having  set  for  some 
days  it  is  ready  to  be  slabbed  and  cut  into  cakes. 

A  potash  soap  may  be  made  by  the  cold  process  just  as 
readily  as  a  soda  soap.  Soaps  of  this  type  may  be  made 
by  either  of  these  formulae  in  a  crutcher: 

Olive  oil   foots 600 

Potash  lye,  18  degs.  B.  hot,  20  degs.  B.  cold. .  660 
or 

Corn   oil 800 

Rosin    200 

Potash  lye,  27  degs.  B 790 

Water    340 

Heat  the  oils  to  190  degs.  F.,  add  the  lye  and  crutch 
until  the  soap  begins  to  bunch,  when  it  is  ready  to  be  run 
into  barrels  where  the  saponification  will  be  completed. 

Semi-boiled  soaps  differ  from  those  made  by  the  cold 
process  in  temperature.  In  making  semi-boiled  soaps  the 
fats  are  usually  heated  to  140°  F.  The  addition  of  the 
44 


SOAP-MAKING    METHODS 

lye  raises  the  temperature  to  180° — 200°  F.  when  saponifi- 
cation  takes  place. 

CARBONATE    SAPONIFICATION. 

The  method  of  the  formation  of  soap  by  the  utilization 
of  the  fatty  acid  directly,  from  which  the  glycerine  has  al- 
ready been  removed  by  some  method  of  saponification 
other  than  with  caustic  soda,  and  neutralizing  this  with 
alkali,  is  becoming  increasingly  popular.  The  glycerine  is 
more  easily  recovered  from  a  previous  cleavage  of  the 
fats  or  oils,  but  a  soap  made  from  the  mixed  fatty  acids 
thus  obtained  is  seldom  white  in  color  and  retains  an  un- 
pleasant odor.  Since  soda  ash  or  sodium  carbonate  is 
cheaper  than  caustic  soda  and  readily  unites  with  a  fatty 
acid,  it  is  used  as  the  alkali  in  the  carbonate  saponification. 
The  process  is  similar  to  that  already  given  under  Rosin 
Saponification.  About  19  per  cent,  by  weight  of  the  fatty 
acids  employed  of  58  per  cent,  soda  ash  is  dissolved  in 
water  until  it  has  a  density  of  30  degs.  B.,  and  the  solu- 
tion is  run  into  the  kettle,  which  is  usually  equipped  with  a 
removable  agitator.  The  fatty  acids,  previously  melted,  are 
then  slowly  added  while  the  mixture  is  boiled  with  open 
steam  and  agitated  with  the  stirring  device.  The  fatty 
acids  instantly  unite  with  the  carbonate  and  rise  in  the 
kettle,  due  to  the  generation  of  carbon  dioxide,  and  care 
must  be  exercised  to  prevent  boiling  over.  After  all  the 
fatty  acid  has  been  added,  and  the  mass  is  boiled  through 
the  saponification  must  be  completed  with  caustic  soda,  as 
there  is  as  yet  no  practical  method  known  which  will 
split  a  fat  entirely  into  fatty  acid  and  glycerine.  Thus 
about  10  per  cent,  of  the  fatty  acids  are  true  neutral  fats 
and  require  caustic  soda  for  their  saponification.  This  is 
then  added  and  the  soap  completed,  as  in  full-boiled  soaps. 

In  carrying  out  this  method  upon  a  large  scale,  large 

45 


SOAP-MAKING    MANUAL 

quantities  of  carbon  dioxide  are  formed  during  the  boiling 
of  the  soap,  which  replaces  a  quantity  of  the  air  contained 
therein.    The  kettle  room  should  therefore  be  well  vend 
lated,  allowing  for  a  large  inflow  of  fresh  air  from  out 
of  doors. 


CHAPTER    IV 

Classification  of  Soaps. 

In  considering  the  many  different  varieties  of  soaps, 
their  classification  is  purely  an  arbitrary  one.  No  definite 
plan  can  be  outlined  for  any  particular  brand  to  be  manu- 
factured nor  can  any  very  sharp  distinction  be  drawn  be- 
tween the  many  soaps  of  different  properties  which  are 
designated  by  various  names.  It  is  really  a  question  to 
what  use  a  soap  is  to  be  put,  and  at  what  price  it  may 
be  sold.  There  is,  of  course,  a  difference  in  the  appear- 
ance, form  and  color,  and  then  there  are  soaps  of  special 
kinds,  such  as  floating  soaps,  transparent  soaps,  liquid 
soaps,  etc.,  yet  in  the  ultimate  sense  they  are  closely  allied, 
because  they  are  all  the  same  chemical  compound, 
varying  only  in  their  being  a  potash  or  soda  soap,  and  in 
the  fatty  acids  which  enter  into  combination  with  these 
alkalis.  Thus  we  can  take  a  combination  of  tallow 
and  cocoanut  oil  and  make  a  great  many  presumably  dif- 
ferent soaps  by  combining  these  substances  with  caustic 
soda,  by  different  methods  of  manufacture  and  by  incor- 
porating various  other  ingredients,  as  air,  to  form  a  float- 
ing soap,  alcohol  to  make  a  transparent  soap,  dyestuffs  to 
give  a  different  color,  etc.,  but  essentially  it  is  the  same 
definite  compound. 

The  manufacturer  can  best  judge  the  brand  of  soaps  he 
desires  to  manufacture,  and  much  of  his  success  depends 
upon  the  name,  package,  shape,  color  or  perfume  of  a 
cake  of  soap.  It  is  the  consumer  whom  he  must  please 
and  many  of  the  large  selling  brands  upon  the  market 
today  owe  their  success  to  the  above  mentioned  details. 
The  great  majority  of  consumers  of  soap  know  very  little 

47 


SOAP-MAKING     MANUAL 

concerning  soap,  except  the  fact  that  it  washes  or  has  a 
pleasant  odor  or  looks  pretty,  and  the  manufacturer  of 
soap  must  study  these  phases  of  the  subject  even  more 
carefully  than  the  making  of  the  soap  itself. 

For  a  matter  of  convenience  we  will  classify  soap  under 
three  general  divisions : 

I.  Laundry   soaps,   including   chip    soaps,    soap   powders 
and  scouring  soaps. 

II.  Toilet    soaps,    including    floating    soap,    castile   soap, 
liquid  soap,  shaving  soap,  etc. 

III.  Textile  soaps. 

LAUNDRY   SOAP. 

The  most  popular  household  soap  is  laundry  soap.  A 
tremendous  amount  of  this  soap  is  consumed  each  day  in 
this  country,  and  it  is  by  far  manufactured  in  larger  quan- 
tities than  any  other  soap.  It  is  also  a  soap  which  must 
be  sold  cheaper  than  any  other  soap  that  enters  the 
home. 

The  consumers  of  laundry  soap  have  been  educated  to 
use  a  full  boiled  settled  rosin  soap  and  to  make  a  good 
article  at  a  price  this  method  should  be  carried  out,  as  it  is 
the  one  most  advisable  to  use.  The  composition  of  the  fats 
entering  into  the  soap  depends  upon  the  market  price  of 
these,  and  it  is  not  advisable  to  keep  to  one  formula  in  the 
manufacture  of  laundry  soap,  but  rather  to  adjust  the 
various  fatty  ingredients  to  obtain  the  desired  results  with 
the  cheapest  material  that  can  be  purchased.  It  is  impos- 
sible to  use  a  good  grade  of  fats  and  make  a  profit  upon 
laundry  soap  at  the  price  at  which  it  must  be  retailed.  The 
manufacturer  of  this  grade  of  soap  must  look  to  the  by- 
product, glycerine,  for  his  profit  and  he  is  fortunate  indeed 
if  he  realizes  the  entire  benefit  of  this  and  still  produces 
a  superior  piece  of  laundry  soap. 


CLASSIFICATION     OF    SOAPS 

SEMI-BOILED  LAUNDRY  SOAPS. 

It  is  advantageous  at  times  to  make  a  laundry  soap  by 
a  method  other  than  the  full  boiled  settled  soap  pro- 
cedure as  previously  outlined.  This  is  especially  the  con- 
dition in  making  a  naphtha  soap,  in  which  is  incorporated 
naphtha,  which  is  very  volatile  and  some  of  the  well  known 
manufacturers  of  this  class  of  soap  have  adopted  this 
process  entirely.  A  laundry  soap  containing  rosin  cannot 
be  advantageously  made  by  the  cold  process,  as  the  soap 
thus  made  grains  during  saponification  and  drops  a  por- 
tion of  the  lye  and  filling  materials.  By  making  a  semi- 
boiled  soap  this  objection  is  overcome.  The  half  boiled 
process  differs  from  the  cold  process  by  uniting  the  fats 
and  alkalis  at  a  higher  tempera'ture. 

To  carry  out  this  process  the  following  formulae  have 
been  found  by  experience  to  give  satisfactory  results. 

I.  Ibs. 

Tallow 100 

Rosin    60 

Soda  Lye,  36°  B 80 

II. 

Tallow    100 

Rosin    60 

Silicate  of  Soda  25 

Soda  Lye,  36°  B 85 

III. 

Tallow    100 

Rosin    100 

Lye,  36°  B 105 

Silicate  of  Soda  25 

Sal  Soda  Solution   20 

49 


SOAP-MAKING    MANUAL 

In  any  of  these  formulas  the  sodium  silicate  (40°  B.) 
may  be  increased  to  the  same  proportion  as  the  fats  used. 
By  so  doing,  however,  twenty  pounds  of  36°  B.  lye  must 
he  added  for  every  hundred  pounds  of  silicate  additional 
to  that  indicated  or  in  other  words,  for  every  pound  of 
silicate  added  20  per  cent,  by  weight  of  36°  B.  lye  must 
be  put  into  the  mixture.  The  rosin  may  also  be  replaced 
by  a  previously  made  rosin  soap. 

To  make  a  semi-boiled  soap,  using  any  of  the  above 
formulae,  first  melt  the  rosin  with  all  or  part  of  the  fat, 
as  rosin  when  melted  alone  readily  decomposes.  When 
the  mixture  is  at  150°  F.  run  it  into  the  crutcher  and  add 
the  lye.  Turn  on  sufficient  dry  steam  to  keep  the  tempera- 
ture of  the  soap  at  about  150°  F.  in  the  winter  or  130°  F. 
in  summer.  After  the  mass  has  been  mixed  for  half  an 
hour,  by  continuously  crutching  the  soap  it  will  at  first 
thicken,  then  grain  and  it  may  again  become  thick  before 
it  becomes  smooth.  When  the  mass  is  perfectly  smooth 
and  homogeneous  drop  into  a  frame  and  crutch  in  the 
frame  by  hand  to  prevent  streaking.  After  standing  the 
required  length  of  time  the  soap  is  finished  into  cakes  as 
usual. 

SETTLED  ROSIN    SOAP. 

Settled  rosin  soaps  are  made  from  tallow,  grease,  cotton- 
seed oil,  bleached  palm  oils  of  the  lower  grades,  corn  oil, 
soya  bean  oil,  arachis  oil,  distilled  garbage  grease,  cotton 
seed  foots  or  fatty  acids  together  with  an  addition  of  rosin, 
varying  from  24  per  cent,  to  60  per  cent,  of  the  fatty  acids 
which  should  titer  from  28  to  35.  A  titer  lower  than  28 
will  prevent  the  finished  kettle  of  soap  from  being  capable 
of  later  taking  up  the  filling  materials.  As  has  already 
been  stated  under  hardened  oils,  these  being  very  much 
higher  in  titer  allow  a  greater  percentage  of  rosin  to  be 
added.  Thus  hardened  fish  oils  and  cottonseed  oil  are 

50 


CLASSIFICATION     OF     SOAPS 

gradually  being  more  extensively  employed  in  soaps  of  this 
character. 

The  procedure  of  handling  the  kettle  is  similar  to  that 
given  under  full  boiled  soap.  The  stock  is  steamed  out 
into  a  settling  tank  and  allowed  to  settle  over  night,  after 
which  it  is  pumped  into  the  soap  kettle.  Having  stocked  the 
kettle,  open  steam  is  turned  on  and  10°-12°  B.  lye  is  run  in, 
while  using  a  steam  pressure  of  ninety  to  one  hundred 
pounds  in  order  to  prevent  too  great  a  quantity  of  conden- 
sation of  the  steam,  the  water  thus  being  formed  weaken- 
ing the  lye.  If  a  steam  pressure  of  fifty  to  sixty  pounds  is 
available,  a  stronger  lye  (20°  B.)  should  be  added.  Care 
must  be  taken  not  to  allow  the  lye  to  flow  in  too  rapidly 
or  the  soap  will  not  grain.  The  saponification  is  only  at- 
tained by  prolonged  boiling  with  sufficient  lye  of  proper 
strength.  When  saponification  has  taken  place,  the  mass 
begins  to  clear  and  a  sample  taken  out  with  a  paddle  and 
cooled  should  show  a  slight  pink  with  a  1  per  cent,  alcoholic 
phenolphthalein  solution. 

It  may  be  stated  here  that  in  using  this  indicator  or  any 
other  to  test  the  alkalinity  of  soap,  the  soap  should  always 
be  cooled  and  firm,  as  whenever  water  is  present,  the  disso- 
ciation of  the  soap  thereby  will  always  react  alkaline.  When 
this  state  is  reached  the  mass  is  ready  for  graining,  which 
is  accomplished  by  distributing  salt  brine  or  pickle  or 
spreading  dry  salt  over  the  surface  of  the  soap.  The 
kettle  is  then  thoroughly  boiled  until  the  mass  shows  a 
soft  curd  and  the  lye  drops  clearly  from  a  sample  taken 
out  with  a  trowel  or  paddle.  The  steam  is  then  shut  off 
and  the  soap  allowed  to  settle  over  night.  The  lyes  are 
then  run  off  to  the  spent  lye  tank  for  glycerine  recovery. 
In  saponifying  a  freshly  stocked  kettle  it  is  apt  to  bunch. 
To  prevent  this  salt  is  added  at  various  times  to  ap- 
proximately one  per  cent,  of  the  fat  used. 

51 


SOAP-MAKING    MANUAL 

If,  by  any  possibility  the  soap  has  bunched,  this  condition 
may  be  remedied  by  the  addition  of  more  strong  lye  and 
boiling  until  it  is  taken  up.  To  work  a  kettle  to  its  full 
capacity  it  is  advisable  to  make  two  "killing"  changes. 
First  add  about  75  per  cent,  of  the  fat  and  grain  as  directed. 
Run  off  the  spent  lyes  and  then  add  the  remainder  of  the 
stock  and  repeat  the  process.  When  the  spent  lye  has  been 
run  to  storage,  the  open  steam  is  again  turned  on  and 
18°  B  lye  gradually  allowed  to  run  in.  The  rosin  is  now 
broken  up  and  put  into  the  kettle,  or  a  previously  made 
rosin  soap  is  pumped  in. 

Lye  is  then  added  until  the  soap  has  a  sharp  taste  after 
about  three  hours  of  continous  boiling,  or  when  the  soap 
is  in  the  closed  state.  More  lye  should  then  be  run  into 
the  kettle  to  grain  the  soap  well,  the  grain  not  being  too 
small.  Then  allow  the  soap  to  settle  over  night  and  draw 
off  the  strengthening  lye.  The  next  day  again  boil  up 
the  kettle  and  add  water  until  the  soap  thins  out  and  rises 
or  swells  high  in  the  kettle.  A  sample  taken  out  at  this 
stage  upon  a  hot  trowel  should  run  off  in  large  flakes. 
The  surface  of  the  soap  should  be  bright  and  shiny. 

If  the  sample  clings  to  the  trowel,  a  slight  addition  of 
lye  will  remedy  this  defect.  The  kettle  is  then  allowed  to 
rest,  to  drop  the  nigre  and  to  cool  for  some  time,  depending 
upon  the  size  of  the  kettle.  The  proper  temperature  is 
such  that  after  having  been  pumped  to  the  crutcher  and  the 
filling  materials  having  been  added,  a  thermometer  placed 
into  the  mass  should  indicate  128°-135°  F.  after  the  crutcher 
has  run  from  ten  to  fifteen  minutes.  The  filling  material 
may  consist  of  from  7-9  per  cent,  of  sal  soda  solution, 
36°-37°  B.  warm  or  just  enough  to  close  up  the  soap  and 
make  it  rise  high  in  the  center  of  a  screw  crutcher  and 
make  it  cling  close  to  a  warm  trowel.  Other  fillers  such 
as  outlined  below  are  added  at  this  point. 

52 


CLASSIFICATION     OF    SOAPS 

An  addition  of  from  2-3  per  cent,  of  a  special  mineral  oil 
for  this  purpose  will  impart  a  finish  to  the  soap  and  3-5 
per  cent,  starch  added  prevents  the  soap  from  cracking  in 
the  frames.  Other  filling  material  as  silicate  of  soda,  borax, 
talc  or  silex  are  used.  Aftej  the  filling  material  has  been 
thoroughly  crutched  through  the  soap  it  is  framed,  and. 
after  being  several  days  in  the  frame  to  solidify  and  cool 
the  soap  is  ready  for  slabbing,  pressing  and  wrapping. 

In  order  to  more  definitely  illustrate  the  composition  of 
the  mixture  of  fats  and  oils  entering  into  the  formation  of 
a  laundry  soap  a  typical  formula  may  be  given  for  such 
a  soap  containing  40  per  cent,  rosin  added  to  the  amount 
of  fats  used: 

Ibs. 

Grease    7,000 

Tallow   4,000 

Corn  Oil  7,000 

Cottonseed  Oil    3,000 

Rosin    8,400 

The  following  have  been  found  to  be  satisfactory  filling 
materials  and  are  calculated  upon  the  basis  of  a  1,400-pound 
frame  of  soap. 

I.  Ibs. 

Sodium  Silicate,  38°-40°  B 100 

Mineral   Oil   25 

Sal  Soda  Solution,  36°  B 80 

Borax   1 

II. 

Sal  Soda  Solution,  36°  B 80 

Mineral  Oil    25 

Sodium   Silicate    60 

S3 


SOAP-MAKING     MANUAL 

III. 

Soda  Ash   10 

Sal  Soda  55 

Sodium  Silicate  115 

Mineral  Oil    40 

Brine  (Saturated  Solution) 10 

IV. 

Sodium   Silicate    100 

Silex  or  Talc    200 

Soda  Ash   50 

V. 

Sal  Soda  Solution,  36°  B 90 

Sodium  Silicate    50-60 

Mineral  Oil    25 

Borax  Solution,  25°  B.  (hot) 15 

CHIP   SOAP. 

Chip  soap  is  used  extensively  in  laundries  but  is  also 
used  largely  in  other  branches.  It  may  be  made  either 
as  a  settled  soap  or  by  the  cold  made  process. 

To  make  a  full  boiled  settled  chip  soap,  proceed  as 
directed  under  settled  laundry  soap.  The  kettle  is  stocked 
with  light  grease  or  a  mixture  of  grease  with  corn  oil  or 
other  cheap  oils.  For  this  kind  of  soap  the  rosin  is  elim- 
inated. 

Chip  soap  may  be  filled  as  well  as  laundry  soap.  This 
is  done  in  the  crutcher  and  the  following  adulterations  are 

suitable. 

Ibs. 

Settled  Soap    700 

Soda  Ash    35 

Sodium  Silicate 215 

or 

Settled  Soap   700 

54 


CLASSIFICATION    OF    SOAPS 

Silicate  of  Soda 560 

Soda  Ash  18 

Carbonate  of  Potash,  26°  B 50 

The  cheapest  method  of  drying  is  by  running  this  soap 

through  a  drying  machine  and  this  is  the  procedure  usually 

carried  out  for  making  dried  chip  soap. 

COLD   MADE  CHIP  SOAPS. 

To  make  chip  soaps  by  the  cold  process  a  sweet  tallow  of 
low  percentage  of  free  fatty  acid  should  be  employed.  The 
tallow  is  heated  to  120°  to  135°  F.  and  the  lye  run  in 
slowly  at  first  and  then  the  silicate  of  soda  is  added.  The 
mass  is  then  mixed  until  a  finger  drawn  through  the 
soap  leaves  a  slight  impression,  then  dropped  into  frames 
or  barrels.  Soaps  containing  a  small  percentage  of  fat 
should  be  well  covered  in  the  frame  for  twenty-four  hours 
to  retain  their  heat  and  insure  proper  saponification.  The 
following  formulae  are  suitable : 

I.  Ibs. 

Tallow    1,200 

Soda  Lye,  25°  B 850 

Sodium    Silicate    750 

II. 

Tallow    475 

Ceylon  Cocoanut  Oil  100 

Soda  Lye,  37°  B 325 

Potash  Lye,  37°   B 56 

III. 

Tallow 500 

Soda  Lye,  37y2°  B 297 

Sodium  Silicate  416 

Potash  Lye,  37y2°   B 

55 


SOAP-MAKING     MANUAL 

IV. 

Tallow    450 

Soda  Lye,  37^°  B 255 

Sodium  Silicate 450 

Potash  Lye,  37V9°  B 50 

V. 

Tallow   450 

Soda  Lye,  35°   B 470 

Sodium    Silicate    650 

VI. 

Tallow    420 

Sodium   Silicate    600 

Soda  Lye,  37^°  B 270 

UNFILLED    CHIP    SOAP. 

A  very  good  grade  of  chip  soap  is  made  by  employing 
no  filling  material  whatsoever,  but  unfortunately  the  price 
of  this  soap  has  been  cut  to  such  an  extent  that  these  can 
not  compete  with  a  filled  chip.  A  number  of  the  best  soaps 
of  this  kind  are  made  from  a  settled  soap  using  a  light 
grease  with  corn  oil.  A  soap  of  this  nature  is  made  as 
follows. 

Ibs. 

Settled    Soap    800 

Sal  Soda  Solution,  36°-37°  B 252 

Soda    Ash    182 

If  this  soap  is  run  into  frames  it  may  be  stripped  and 
chipped  in  two  days. 

SOAP    POWDERS. 

Soap  powders  have  become  so  great  a  convenience 
as  a  general  cleansing  agent  that  to  eliminate  them 
from  the  household  necessities  would  mean  much  un- 

56 


CLASSIFICATION    OF    SOAPS 

necessary  energy  and  work  to  the  great  number  of 
consumers  of  this  product.  They  may  be  manufactured  so 
heaply  and  still  be  efficient,  that  their  use  has  almost 
become  universal  for  cleansing  and  scouring  purposes. 
The  uses  to  which  soap  and  scouring  powders  are  adapted 
are  too  well  known  to  enter  into  a  description  of  their 
employment.  Since  they  offer  a  greater  profit  to  the  man- 
ufacturer than  ordinary  household  soap,  maay  brands  are 
extensively  advertised. 

Numerous  combinations  for  soap  powders  might  be  cited 
and  it  is  a  simple  matter  to  vary  the  ingredients  as  to 
fat  content  and  manufacture  a  powder  of  this  sort  as  low 
as  a  cent  a  pound.  Many  substances  are  incorporated  with 
soap,  such  as  salt,  soda  ash,  tripoli,  crushed  volcanic  de- 
posits, ground  feldspar,  infusorial  earth  of  various  kinds, 
silex,  etc.  In  addition  to  these  various  fillers,  compounds 
with  true  cleansing  and  bleaching  properties,  in  addition  to 
soap,  are  added,  such  as  the  salts  of  ammonium  (sal  am- 
moniac, carbonate  of  ammonia),  sodium  perborate  and 
the  peroxides  of  various  metals.  The  public,  however, 
have  been  accustomed  to  receive  a  large  package  of 
soap  or  scouring  powder  for  a  small  amount  of  money 
and  it  is  a  difficult  matter  for  the  manufacturer  to  add 
more  expensive  substances  of  this  nature  to  his  product, 
to  increase  its  efficiency,  without  raising  the  price  or 
decreasing  the  size  of  the  package. 

In  manufacturing  soap  powders,  the  dried  soap  chips 
might  be  mixed  with  the  filler  and  alkali  and  then 
pulverized.  This  method  is  not  extensively  employed 
nevertheless.  The  process  which  is  the  most  economical 
is  one  whereby  the  ingredients  are  mixed  in  a  spe- 
cially adapted  mixer  for  heavy  material  until  dry  and 
then  run  directly  to  the  crusher  and  pulverizer,  after 
which  it  is  automatically  packed,  sealed  and  boxed. 

57 


SOAP-MAKING    MANUAL 

Another  method  of  procedure  is  to  run  out  the  mix- 
ture from  the  crutcher  to  the  frames,  which  are  stripped 
before  the  soap  cools,  and  is  cut  up  at  once,  for  if  it 
hardens  it  could  not  be  cut  with  wires.  It  is  better,  how- 
ever, to  run  the  mixture  into  sheets  upon  a  specially  con- 
structed floor  and  break  up  the  mass  when  cool. 

Formulae  for  soap  powders  which  have  been  found 
to  be  suitable  for  running  dry  in  the  mixer  follow: 

I 

Soda  ash,  58  per  cent 42  Ibs. 

Silica    220     " 

Settled  soap  (usually  cottonseed).     25     " 
Salt   10     " 

II 

Soap    (settled   cottonseed) 40  Ibs. 

Soda  ash,  58  per  cent 60     " 

III 

Settled    soap 100  Ibs. 

Soda  ash,  58  per  cent 400     " 

Fillers  in  varying  proportions  may  replace  the  soda 
ash  in  the  above  formulae.  It  is  of  course  understood 
that  the  soap  has  been  previously  made  and  run  as 
molten  soap  into  the  crutcher. 

The  following  soap  powders  will  not  dry  up  in  the 
crutcher  upon  running,  but  are  of  the  class  which  may 
be  framed  or  run  on  the  floor  to  solidify: 

I 

Soap    850  Ibs. 

Filler    400     " 

Sal  soda  solution,  20  degs.  B 170     " 

58 


CLASSIFICATION     OF    SOAPS 

II 

Soap   650  Ibs. 

Filler    550     " 

Sal  soda  solution,  20  degs.  B 340     " 

III 

Soap   80  Ibs. 

Filler    550     " 

Sal  soda  solution 170     " 

IV 

Soap  (settled  tallow) 800  Ibs. 

Filler 400 

Sal   soda   solution 170 

Water    100     " 

V 

First  saponify  100  parts  house  grease  and  100  parts 
ordinary  grease  and  make  a  run  soap.  Then  use  in 
crutcher  either: 

Soap   "...  400  Ibs. 

Filler    575     " 

Hot  water    60     " 

or 

Soap   200  Ibs. 

Hot  water 200     " 

Filler    625     " 

It  would  be  a  simple  matter  to  write  numerous  addi- 
tional formulae,  but  the  above  are  typical.  The  manu- 
facturer must  judge  for  himself  just  what  filling 
material  to  use.  The  filler  indicated  in  the  above 
formulae  is  therefore  left  open.  A  few  formulae  for 
more  expensive  powders  than  those  given  recently  ap- 
peared among  others  in  the  "Seifensieder  Zeitung"*: 


•Seifensieder  Ztg.,  40,  47,  1266  (1913). 
59 


SOAP-MAKING     MANUAL 

I 

Powdered    soap    90  Ibs. 

Sodium  perborate    10 

The  perborate  should  be  added  when  the  powder  is 
perfectly  dry  or  it  loses  its  bleaching  properties. 

II 
Soap  powder,  20  per  cent.  fat. 

Cocoanut   oil   fatty   acids 25  Ibs. 

Olein    25     " 

Bone  fat 70     " 

Soda    lye,    30    degs.    B 90     " 

Water 150     " 

Ammonium  carbonate    125 

III 
Soap  powder,  10  per  cent.  fat. 

Cocoanut    oil   fatty   acids 20  Ibs. 

Olein    10     " 

Bone   fat 20     " 

Soda   lye,    30   degs.    B 30     " 

Water    175     " 

Ammonium   carbonate 175 

LIGHT    OR    FLUFFY    POWDERS. 

Light  or  fluffy  powders  containing  35-45%  moisture  can 
be  made  in  two  ways.  The  first  method  requiring  a  min- 
imum equipment  is  to  mix  the  powder  and  sal  soda  in  a 
mixer,  allow  it  to  stand  in  frames  for  a  week  to  crystallize 
or  spread  it  on  the  floor  for  a  few  hours  to  dry  and  then 
grinding  it. 

The  continuous  method  finishes  the  powder  in  a  few  min- 
utes and  with  a  minimum  amount  of  labor.  By  this 
process  the  various  ingredients,  soap,  soda  ash  solution,  etc., 
are  measured,  run  by  gravity  into  the  mixer,  mixed  and  the 
molten  mass  run  over  the  crystallizer  or  chilling  rolls  thru 

60 


CLASSIFICATION     OF     SOAPS 

which  either  cold  water  or  brine  is  pumped.  From  the  roll 
the  powder  is  scraped  off  clean  ab  y  knife,  passes  to  a 
screen  which  sends  the  tailings  to  a  grinder,  falls  into  a 
storage  bin  from  whence  it  is  weighed  and  packed  by  an 
automatic  weighing  machine  into  cartons  made  up  in  most 
cases  by  another  machine.  Due  to  the  large  percentage  of 
moisture  contained  in  these  soap  powders  the  carton  is 
generally  wrapped  in  wax  paper  to  aid  in  the  prevention  of 
the  escape  of  moisture. 

SCOURING  POWDERS. 

Scouring  powders  are  very  similar  to  soap  powders  and 
differ  only  in  the  filler  used.  We  have  already  considered 
these  fillers  under  scouring  soap,  from  which  they  do  not 
differ  materially.  They  are  usually  insoluble  in  water  to 
aid  in  scouring.  The  mixer  used  for  substances  of  this 
kind  in  incorporating  the  soap  and  alkali  must  be  of 
strong  construction. 

SCOURING  SOAP. 

Scouring  soaps  resemble  soap  powders  very  closely 
in  their  composition,  in  that  they  are  a  combination  of 
soap  and  filling  material.  Since  more  lather  is  required 
from  a  scouring  soap  than  in  soap  powders,  a  cocoa- 
nut  oil  soap  is  generally  used.  The  usual  filling  ma- 
terial used  is  silex.  The  greatest  difficulty  in  the  manu- 
facture of  scouring  soap  is  the  cracking  of  the  finished 
cake.  This  is  usually  due  to  the  incorporation  of  too 
great  an  amount  of  filler,  or  too  high  a  percentage  of 
moisture. 

In  manufacturing  these  soaps  the  cocoanut  oil  is 
saponified  in  the  crutcher  with  38  degs.  B.  lye,  or 
previously  saponified  as  a  run  soap,  as  already  de- 
scribed under  "Marine  Soaps."  To  twenty-five  parts 
of  soap  are  added  a  percentage  of  38  degs.  B.  sal  soda 

6] 


SOAP-MAKING     MANUAL 

or  soda  ash  solution,  together  with  a  small  quantity  of 
salt  brine.  To  this  mixture  in  the  crutcher  seventy-five 
parts  of  silex  are  then  added,  and  a  sufficient  amount  of 
hot  water  to  make  the  mass  flow  readily.  Care  must 
be  exercised  to  not  add  too  great  a  quantity  of  water 
or  the  mass  will  crack  when  it  cools.  The  mass  is 
then  framed  and  cut  before  it  sets,  or  poured  into 
molds  and  allowed  to  set.  While  silex  is  the  most 
extensively  used  filler  for  scouring  soaps,  it  is  feasible 
to  incorporate  other  substances  of  like  character,  al- 
though it  is  to  be  remembered  that  the  consumer  is  accus- 
tomed to  a  white  cake,  such  as  silex  produces.  Any 
other  material  used  to  replace  silex  should  also  be  as 
tine  as  this  product. 

FLOATING    SOAP. 

Floating  soap  occupies  a  position  midway  between  laun- 
dry and  toilet  soap.  Since  it  is  not  highly  perfumed  and 
a  large  piece  of  soap  may  be  purchased  for  small  cost,  as 
is  the  case  with  laundry  soap,  it  is  readily  adaptable  to 
general  household  use.  Floating  soap  differs  from  ordinary 
soap  in  having  air  crutched  into  it  which  causes  the  soap 
to  float  in  water.  This  is  often  advantageous,  especially 
as  a  bath  soap,  and  undoubtedly  the  largest  selling  brand 
of  soap  on  the  American  market  today  ib  a  floating  soap. 

In  the  manufacture  of  floating  soap  a  high  proportion  cf 
cocoanut  oil  is  necessary.  A  most  suitable  composition  is 
one  part  cocoanut  oil  to  one  part  of  tallow.  This  is  an 
expensive  stock  for  the  highest  grade  of  soap  and  is  Usually 
cheapened  by  the  use  of  cottonseed  or  various  other  liquid 
oils.  Thus  it  is  possible  to  obtain  a  floating  soap  from  a 
kettle  stocked  with  30  per  cent,  cocoanut  oil,  15  per  cent, 
cottonseed  oil  and  55  per  cent,  tallow.  With  this  quality 
of  soap,  however,  there  is  a  possibility  of  sweating  and 

62 


CLASSIFICATION    OF    SOAPS 

rancidity,  and  of  the  soap  being  too  soft  and  being  poor 
in  color. 

The  process  of  manufacture  is  to  boil  the  soap  in  an  or- 
dinary soap  kettle,  after  which  air  is  worked  into  the  hot 
soap  by  a  specially  constructed  crutcher,  after  which  the 
soap  is  framed,  slabbed,  cut  into  cakes  and  pressed. 

Concerning  the  boiling  of  the  soap,  the  saponification 
must  be  carefully  carried  out,  as  the-  high  proportion  of 
cocoanut  oil  may  cause  a  violent  reaction  in  the  kettle  caus- 
ing it  to  boil  over. 

The  method  of  procedure  is  the  same  as  for  a  settled 
soap  up  to  the  finishing.  When  the  mass  is  finally  settled 
after  the  finish,  the  soap  should  be  more  on  the  "open"  side, 
and  the  object  should  be  to  get  as  long  a  piece  of  goods 
as  possible. 

Due  to  its  high  melting  point,  a  much  harder  crust 
forms  on  the  surface  of  a  floating  soap  and  in  a  greater 
proportion  than  on  a  settled  soap  during  the  settling.  In  a 
large  kettle,  in  fact,  it  has  been  found  impossible  to  break 
through  this  crust  by  the  ordinary  procedure  to  admit  the 
skimmer  pipe.  Much  of  the  success  of  the  subsequent  opera- 
tions depends  upon  the  completeness  of  the  settling,  and  in 
order  to  overcome  the  difficulties  occasioned  by  the  forma- 
tion of  the  crust  everything  possible  should  be  done  in  the 
way  of  covering  the  kettle  completely  to  enable  this  period 
of  settling  to  continue  as  long  as  possible. 

When  the  soap  is  finished  it  is  run  into  a  specially  con- 
structed U-shape  crutchcr,  a  Strunz  crutcher  is  best  adapt- 
ed to  this  purpose,  although  a  rapidly  revolving  upright 
screw  crutcher  has  been  found  to  give  satisfaction  upon  a 
smaller  scale,  and  a  sufficient  quantity  of  air  beaten  into 
the  soap  to  make  it  light  enough  to  float.  Care  must  be 
taken  not  to  run  the  crutcher  too  rapidly  or  the  soap  will 
be  entirely  too  fobby.  During  this  operation  the  mass  of 

63 


SOAP-MAKING    MANUAL 

soap  increases  in  bulk,  and  after  it  has  been  established 
how  much  air  must  be  put  into  the  soap  to  satisfy  the  re- 
quirements, this  increase  in  bulk  is  a  criterion  to  estimate 
when  this  process  is  completed. 

It  is  of  course  understood  that  the  longer  the  crutching 
continues  the  greater  quantity  of  air  is  incorporated  and  the 
increase  of  volume  must  be  established  for  a  particular 
composition  by  sampling,  cooling  the  sample  rapidly  and 
seeing  if  it  floats  in  water.  If  the  beating  is  continued  too 
long  an  interval  of  time,  the  finished  soap  is  too  spongy 
and  useless. 

The  temperature  of  the  mass  during  crutching  is  most 
important.  This  must  never  exceed  158  degrees  F.  At 
159  degrees  F.  the  operation  is  not  very  successful,  yet 
the  thermometer  may  indicate  140  degrees  F.  without  inter- 
fering with  this  operation.  If,  however,  the  temperature 
drops  too  low,  trouble  is  liable  to  be  met  with,  by  the  soap 
solidifying  too  quickly  in  the  frames. 

When  the  crutching  is  completed,  the  soap  is  allowed 
to  drop  into  frames  through  the  valve  at  the  bottom  of  the 
crutcher  and  rapidly  crutched  by  the  hand  in  the  frames 
to  prevent  large  air  spaces  and  then  allowed  to  cool.  It 
is  an  improvement  to  jolt  the  frames  as  they  are  drawn 
away  as  this  tends  to  make  the  larger  air  bubbles  float  to 
the  surface  and  thus  reduce  the  quantity  of  waste.  When 
the  soap  has  cooled,  the  frame  is  stripped  and  the  soap 
slabbed  as  usual.  At  this  point  a  layer  of  considerable 
depth  of  spongy  soap  will  be  found  to  have  formed.  This 
of  course  must  be  cut  away  and  returned  to  the  kettle. 
The  last  few  slabs  are  also  often  rejected,  inasmuch  as 
the  weight  of  the  soap  above  them  has  forced  out  so  much 
of  the  air  that  the  soap  no  longer  floats.  As  a  fair  average 
it  may  be  estimated  that  not  more  than  50  to  60  per  cent, 
of  the  soap  in  the  kettle  will  come  out  as  finished  cakes, 

64 


CLASSIFICATION    OF    SOAPS 

the  remaining  40  to  50  per  cent,  being  constituted  by  the 
heavy  crust  in  the  kettle,  the  spongy  tops,  the  botton  slabs 
and  scrapings.  This  soap  is  of  course  reboiled  and  con- 
sequently not  lost,  but  the  actual  cakes  obtained  are  pro- 
duced at  a  cost  of  practically  double  labor. 

It  is  advisable  to  add  a  small  quantity  of  soap  blue  color 
to  the  mass  while  crutching  to  neutralize  the  yellowish 
tint  a  floating  soap  is  liable  to  have. 

Some  manufacturers  add  a  percentage  of  carbonate  of 
soda,  about  3  per  cent.,  to  prevent  the  soap  from  shrinking. 
Floating  soap  may  also  be  loaded  with  sodium  silicate  to 
the  extent  of  about  5  per  cent. 

TOILET  SOAP. 

It  is  not  a  simple  matter  to  differentiate  between  toilet 
soaps  and  various  other  soaps,  because  numerous  soaps  are 
adaptable  to  toilet  purposes.  While  some  soaps  of  this 
variety  are  manufactured  by  the  cold  made  or  semi-boiled 
process,  and  not  milled,  the  consumer  has  become  accus- 
tomed to  a  milled  soap  for  general  toilet  use. 

The  toilet  base  most  extensively  employed  is  a  tallow 
and  cocoanut  base  made  as  a  full  boiled  settled  soap.  The 
manufacture  of  this  base  has  already  been  outlined  and 
really  needs  no  further  comment  except  that  it  is  to  be 
remembered  that  a  suitable  toilet  soap  should  contain  no 
great  excess  of  free  alkali  which  is  injurious  to  the  skin 
Cochin  cocoanut  oil  is  preferable  to  the  Ceylon  cocoanut 
oil  or  palm  kernel  oil,  to  use  in  conjunction  with  the  tal- 
low, which  should  be  a  good"  grade  and  color  if  a  white 
piece  of  goods  is  desired.  The  percentage  of  cocoanut  oil 
may  be  anywhere  from  10  to  25  per  cent.,  depending  upon 
the  kind  of  lather  required,  it  being  remembered  that  co- 
coanut oil  increases  the  lathering  power  of  the  soap. 

In  addition  to  a  tallow  base,  numerous  other  oils  are 
65 


SOAP-MAKING    MANUAL 

used  in  the  manufacture  of  toilet  soaps,  especially  palm 
oil,  palm  kernel  oil,  olive  oil  and  olive  oil  foots,  and  to  a 
much  less  extent  arachis  or  peanut  oil,  sesame  oil  and 
poppy  seed  oil,  oils  of  the  class  of  cottonseed,  corn  and 
soya  bean  oils  are  not  adapted  to  manufacturing  a  milled 
soap,  as  they  form  yellow  spots  in  a  finished  cake  of  soap 
which  has  been  kept  a  short  time. 

Palm  oil,  especially  the  Lagos  oil,  is  much  used  in  mak- 
ing a  palm  base.  As  has  already  been  stated,  the  oil  is 
bleached  before  saponification.  A  palm  base  has  a  yel- 
lowish color,  a  sweetish  odor,  and  a  small  quantity  added 
to  a  tallow  base  naturally  aids  the  perfume.  It  is  especially 
good'  for  a  violet  soap.  The  peculiarity  of  a  palm  oil  base 
is  that  this  oil  makes  a  short  soap.  By  the  addition  of 
some  tallow  or  twenty  to  twenty-five  per  cent,  of  cocoanut 
oil,  or  both,  this  objection  is  overcome.  It  is  a  good  plan 
in  using  a  straight  palm  base  to  add  a  proportion  of  yellow 
color  to  hold  the  yellowish  tint  of  this  soap,  as  a  soap  made 
from  this  oil  continues  bleaching  upon  exposure  to  air  and 
light. 

Olive  oil  and  olive  oil  foots  are  used  most  extensively 
in  the  manufacture  of  castile  soaps.  The  peculiarity  of  an 
olive  oil  soap  is  that  it  makes  a  very  slimy  lather,  and  like 
palm  oil  gives  the  soap  a  characteristic  odor.  An  olive 
oil  soap  is  usually  considered  to  be  a  very  neutral  soap 
and  may  readily  be  superfatted.  Much  olive  oil  soap  is 
used  in  bars  or  slabs  as  an  unmilled  soap  and  it  is  often 
made  by  the  cold  process.  Peanut  oil  or  sesame  and  poppy 
seed  oil  often  replaces  olive  oil,  as  they  form  a  similar 
soap  to  olive  oil. 

In  the  manufacture  of  a  toilet  soap  it  is  hardly  practical 
to  lay  down  a  definite  plan  for  the  various  bases  to  be 
made.  From  the  combination  of  tallow,  palm  oil,  cocoanut 
oil,  palm  kernel  oil,  olive  oil  and  olive  oil  foots,  a  great 

66 


CLASSIFICATION     OF    SOAPS 

many  bases  of  different  proportions  might  be  given.  The 
simplest  method  is  to  make  a  tallow  base,  a  palm  base  and 
an  olive  oil  base.  Then  from  these  it  is  an  easy  matter 
to  weigh  out  any  proportion  of  these  soap  bases  and  ob- 
tain the  proper  mixture  in  the  mill.  If,  however,  as  is 
often  the  case,  a  large  quantity  of  soap  base  of  certain  pro- 
portions of  these,  four  or  even  more  of  these  fats  and  oils 
is  required,  it  is  not  only  more  economical  to  stock  the 
kettle  with  the  correct  proportion  of  these  oils,  but  a  more 
thorough  mixture  is  thus  obtained  *>y  saponifying  these  in 
the  kettle.  In  view  of  the  fact  that  it  is  really  a  question 
for  the  manufacturer  to  decide  for  himself  what  combina- 
tion of  oils  he  desires  for  a  particular  soap  we  will  simply 
outline  a  few  typical  toilet  soap  bases  in  their  simplest 
combination.  It  is  understood  that  these  soaps  are  suitable 
for  milled  soaps  and  are  to  be  made  as  fully  boiled  settled 
soaps.  Palm  kernel  oil  may  be  substituted  for  cocoanut 
oil  in  all  cases. 

TALLOW   BASE. 

Tallow 75-90  parts 

Cocoanut  oil  25-10  parts 

PALM   BASE. 

Bleached  Lagos  palm  oil 75-80  parts 

Cocoanut  oil  25-20  parts 

or 

Tallow    30  parts 

Palm  oil   60  parts 

Cocoanut  oil 10  parts 

OLIVE  OIL  BASE    (WHITE). 

Olive   oil    75-50  parts 

Cocoanut  oil   25-10  parts 

or 

67 


SOAP-MAKING     MANUAL 

Olive  oil 40  parts 

Tallow    40  parts 

Cocoanut   20  parts 

Where  a  green  olive  oil  base  is  desired,  olive  oil  foots 
are  substituted  for  the  olive  oil.  Peanut  oil  may  replace 
the  olive  oil  or  part  of  it,  the  same  being  true  of  sesame 
oil  and  poppy  seed  oil. 

PALM    AND  OLIVE  BASE. 

Palm  oil 50  parts 

Olive  oil 30  parts 

Cocoanut  oil  20  parts 

or 

Palm  oil  20  parts 

Olive  oil 10  parts 

Tallow    50  parts 

Cocoanut  oil  20  parts 

CHEAPER  TOILET  SOAPS. 

It  is  often  necessary  to  manufacture  a  cheaper  grade  of 
soap  for  toilet  purposes  to  meet  the  demand  of  a  certain 
class  of  trade  as  well  as  for  export.  To  accomplish  this 
it  is  of  course  necessary  to  produce  a  very  inferior  product 
and  run  down  the  percentage  of  fatty  acids  contained  in 
the  soaps  by  the  addition  of  fillers  or  to  use  cheaper  oils  in 
manufacturing.  The  most  simple  method  of  filling  a  soap 
is  to  load  it  at  the  mill  with  some  substance  much  less  ex- 
pensive than  the  soap  itself.  Many  of  the  cheaper  toilet 
soaps,  however,  are  not  milled  and  it  is,  therefore,  neces- 
sary to  follow  out  some  other  procedure. 

Milled  soaps,  as  has  just  been  stated,  are  loaded  at  the 
mill.  The  consumers  of  cheaper  toilet  soaps  in  this 
country  are  accustomed  to  a  milled  soap  and  this  grade 
of  soap  for  home  consumption  is  very  often  filled  with 

68 


CLASSIFICATION    OF    SOAPS 

numerous  substances,  but  most  generally  by  adding  starch 
and  talc.  The  addition  of  such  materials  of  course  later 
exhibit  themselves  by  imparting  to  the  cake  of  soap  a 
dead  appearance.  Talc  is  more  readily  detected  in  the 
soap  than  starch  by  washing  with  it,  as  talc  is  insoluble  and 
imparts  a  roughness  to  the  soap,  like  sand  or  pumice,  as 
the  soap  wears  down.  It  may  readily  be  added  to  20  per 
cent,  by  weight.  Starch  is  to  be  preferred  to  talc,  in  load- 
ing a  soap,  as  it  is  not  so  readily  noticeable  in  washing.  It 
leaves  the  cake  itself  absolutely  smooth  although  the  lather 
formed  is  more  shiny.  This  substance  may  be  employed  to 
as  high  a  percentage  as  one-third  the  weight  of  the  soap. 
It  is,  of  course,  possible  to  cheapen  the  best  soap  base  by 
this  method  and  the  price  may  be  further  lowered  by  using 
the  less  expensive  oils  and  fats  to  make  the  soap  base. 

RUN  AND  GLUED  UP   SOAPS. 

A  very  cheap  grade  of  soap  may  be  made  by  making  a 
run  soap  and  adding  the  filler  e.  g.  sodium  silicate  in  the 
kettle  during  saponification.  The  percentage  of  fatty  acids 
may  be  brought  down  to  10  per  cent.,  although  of  course 
a  soap  of  this  type  shrinks  a  whole  lot  upon  exposure. 

In  making  a  "glued  up"  soap  the  procedure  is  the  same 
for  making  the  soap  itself  as  with  a  settled  soap,  except 
that  the  soap  is  finished  "curd"  and  later  filled  in  the 
crutcher.  The  percentage  of  fatty  acids  in  a  soap  of  this 
type  is  seldom  below  50  per  cent. 

The  method  of  "gluing  up"  a  soap  is  best  illustrated  by  a 
typical  soap  of  this  character  in  which  the  kettle  is  charged 
with  the  following  stock. 

Bleached  palm  oil  5  parts 

Distilled  grease   2      " 

Cotton  oil  foots  stock,  63%  fatty  acid.   1      " 
Rosin    .  .  4      " 


SOAP-MAKING     MANUAL 

The  palm  oil  is  first  run  into  the  kettle,  saponified  and 
washed  to  extract  any  glycerine,  then  the  rest  of  the  fats 
and  finally  the  rosin.  The  soap  is  then  finished  and  settled 
as  with  a  boiled  settled  soap.  To  assure  success  it  is 
absolutely  necessary  that  the  soap  settle  as  long  a  period 
as  possible,  or  until  the  temperature  is  about  150  degs.  F. 
The  ideal  temperature  for  carrying  out  the  "gluing  up" 
process  is  140  degs.  F.,  as  at  a  lower  temperature  than 
this  the  soap  is  liable  to  cool  too  quickly  and  not  be 
thoroughly  glued  up.  A  higher  temperature  than  150  degs. 
F.  causes  delay  in  that  the  soap  does  not  properly  take  the 
filler  at  a  higher  temperature  and  the  soap  must  be  kept  in 
the  crutcher  until  the  temperature  drops  to  the  right  point. 

The  soap  is  run  into  the  crutcher  and  the  percentage  of 
fatty  acids  run  down  to  50-55  per  cent,  with  one  of  the 
following  mixtures : 

Sodium  silicate,  59l/20  B 1  part 

Potassium  carbonate,  51°   B 1  " 

or 

Sodium  silicate,  59^°  B 1  part 

Potassium  carbonate,  51°  B 1     " 

Sodium  sulfate,  28°  B 1     " 

From  230  to  300  pounds  of  either  of  these  mixtures  are 
required  for  a  crutcher  holding  2,600  pounds  of  soap. 

The  crutching  is  continued  until  the  mass  is  well  "spiked," 
that  is  to  say,  a  freshly  broken  surface  of  the  soap,  as 
the  crutcher  blade  is  jerked  away,  stands  up  like  shattered 
sheets  in  triangular  form  (A  A  A),  which  retain  their 
shape  perfectly.  When  this  condition  is  realized  the  soap 
is  run  into  frames  which  are  carefully  crutched  by  hand 
to  remove  any  air  spaces.  The  surface  of  the  soap  is  then 
smoothed  down  and  heaped  up  in  the  center.  After  stand- 
ing a  day  to  contract,  the  surface  is  again  leveled  and  a 

70 


CLASSIFICATION    OF    SOAPS 

snugly-fitting  board  placed  on  the  top  of  the  soap  upon 
which  a  weight  is  placed  or  upon  which  the  workman 
treads  and  stamps  until  the  surface  is  flat,  thus  assuring 
the  further  removal  of  air  spaces.  The  soap  remains  in 
the  frame  from  six  to  eight  days  and  is  then  slabbed, 
barred  and  pressed  by  the  usual  method  employed  for 
soaps  thus  handled  without  milling. 

In  a  soap  of  this  nature  no  hard  and  fast  rule  can  be 
laid  down  as  to  the  quantity  of  solution  to  be  used  for 
"gluing  up"  or  the  strength  of  the  solution.  In  a  soap  of 
the  type  described  the  most  satisfactory  appearing  cake 
will  be  obtained  from  a  soap  containing  58  per  cent,  fatty 
acids.  That  is  to  say,  about  8  per  cent,  to  10  per  cent,  rilling 
solution  is  added  per  hundred  pounds  of  soap.  The  filling 
solutions  given  are  very  satisfactory.  Carbonate  of  soda 
should  be  avoided  in  connection  with  sodium  silicate  as  the 
property  of  efflorescing  on  the  surface  of  the  finished  cake 
after  a  short  time  will  prove  detrimental.  To  assure  suc- 
cessful gluing  up  it  is  advisable  to  experiment  upon  a 
small  scale  to  determine  the  exact  extent  to  which  the 
filling  solution  should  be  diluted.  Various  proportions  of 
water  are  added  to  a  certain  quantity  of  the  filled  soap. 
After  the  soap  has  been  filled  in  a  small  receptacle  a 
sample  is  taken  and  rubbed  between  the  fingers.  If  the 
freshly  exposed  surface  is  smooth  and  glossy,  the  filling 
solution  is  weak  enough,  if  rough  it  is  too  strong.  It  is 
of  course  understood  that  the  temperature  must  be  correct, 
140  degs.  to  150  degs.  F.,  or  the  soap  will  be  rough.  By  this 
means  the  operator  can  readily  judge  the  correct  strength 
of  his  filling  solution.  When  properly  carried  out  a  per- 
fectly satisfactory  soap  is  obtained. 
CURD  SOAP. 

The  object  of  a  soap  which  is  finished  "curd"  or  grained, 
is  to  obtain  a  harder  piece  of  goods  from  low  titer  fat  or 


SOAP-MAKING    MANUAL 

to  increase  the  percentage  of  fatty  acids  in  the  finished 
soap.  This  is  still  another  method  of  producing  a  cheap 
grade  of  soap  as  by  its  adoption  the  cheaper  oils  and  fats 
may  be  used  to  obtain  a  firm  piece  of  soap. 

A  typical  charge  for  curd  soap  is: 

Red  oil  63  parts 

Tallow    10      " 

Rosin  27     " 

Cotton  seed  foots  may  be  employed  in  place  of  red  oil 
and  a  tallow  of  too  high  titer  is  not  suitable  for  this  kind 
of  soap. 

The  red  oil  and  tallow  are  first  saponified  with  15  degs. 
B.  lye,  boiler  pressure  80-90  pounds,  18  degs.  B.  lye  for 
lower  steam  pressure,  and  two  washings  given  to  extract 
the  glycerine.  The  rosin  is  added  at  the  strengthening 
change  and  at  the  finish  the  soap  is  "pitched,"  that  is  to 
say,  the  soap  is  settled  over  night  only.  The  next  day  the 
lyes  are  drawn  off  and  a  portion  of  the  nigre  pumped  to 
another  kettle  which  prevents  later  streaking  of  the  soap. 
The  soap  is  then  boiled  with  18  degs.  B.  lye  as  with 
another  strengthening  change  under  closed  steam.  Salt 
brine  or  "pickle,"  15  degs.  B.  is  then  added  and  the  mass 
boiled  with  closed  steam  until  the  brine  reaches  a  density 
of  18  degs.  B.  and  the  kettle  pumped  the  next  day.  A 
soap  of  this  type  requires  either  hand  or  power  crutching 
to  assure  homogeneity  and  prevention  of  streaks.  To  ob- 
viate any  air  spaces  it  is  advisable  to  place  over  the  top 
of  the  frame  a  tightly-fitted  board  which  is  heavily 
weighted  down.  This  soap  is  also  pressed  without  any 
milling. 

COLD    MADE   TOILET    SOAPS. 

Comparatively  little  toilet  soap  is  made  by  the  cold  or 
femi-boiled  processes.  While  thes«  are  the  simplest 

72 


CLASSIFICATION    OF    SOAPS 

methods  of  manufacturing  soaps  the  drawbacks  of  using 
them  are  numerous  and  only  in  a  few  cases  are  they  very 
extensively  employed.  To  make  a  toilet  soap  by  the  cold 
process  a  combination  of  good  grade  tallow  and  cocoanut 
oil  is  required.  It  requires  50  per  cent,  by  weight  of  36 
degs.  B.  lye  to  saponify  a  given  weight  of  tallow  and  50 
per  cent,  of  38  degs.  B.  lye  for  cocoanut  oil.  The  lyes 
are  used  full  strength  or  may  be  reduced  slightly  with 
water  and  the  method  of  procedure  is  the  same  as  alreadj 
given  in  the  general  directions  for  cold  made  soaps. 

Cold  made  soaps  are  readily  filled  with  sodium  silicate 
which  is  added  at  the  same  time  the  stock  is  put  into  the 
crutcher.  In  adding  the  silicate  it  is  necessary  to  add 
additional  lye  to  that  required  for  saponifying  the  fats, 
about  20  per  cent,  of  36  degs.  B.  lye  is  the  proper  amount. 
There  is  of  course  a  certain  amount  of  shrinking  due  to 
the  addition  of  this  filler  and  the  finished  cake  is  exceed- 
ingly hard,  yet  the  author  has  seen  a  good  looking  cake  of 
cheap  soap  made  from  as  high  a  proportion  as  420  parts 
of  tallow  to  600  parts  of  silicate. 

Cold  made  soaps  are  usually  pressed  without  milling, 
although  it  is  readily  feasible  to  mill  a  cold  made  soap 
provided  it  is  not  a  filled  soap  such  as  has  just  been 
described. 

PERFUMING   AND   COLORING   TOILET    SOAPS. 

Equally  important  as  the  soap  itself  or  even  to  a  greater 
extent  is  the  perfume  of  a  toilet  soap.  A  prominent  manu- 
facturer recently  made  the  statement,  which  is  often  the 
truth,  that  it  makes  no  difference  to  the  public  what  kind 
of  soap  you  give  them,  as  long  as  you  put  plenty  of  odor 
into  it.  The  perfuming  of  soaps  is  an  art  in  itself  and  a 
subject  to  be  treated  by  one  versed  in  this  particular 
branch.  We  can  only  take  into  account  the  importance  of 

73 


SOAP-MAKING    MANUAL 

the  perfume  as  related  to  toilet  soap  not  only,  but  the  ne- 
cessity of  adding  a  certain  proportion  of  the  cheaper 
products  of  odoriferous  nature  to  laundry  soap  to  cover 
and  disguise  the  odor  of  even  this  type  of  soap. 

The  price  of  a  cake  of  toilet  soap  to  a  great  extent  de- 
pends upon  the  perfume,  and  the  manufacturer  should  aim 
to  give  the  best  possible  perfume  for  a  certain  price.  He 
should  not  allow  his  personal  likes  or  dislikes  to  enter  into 
the  judgment  of  whether  an  odor  is  good  or  not,  but  sub- 
mit it  to  a  number  of  persons  to  obtain  the  concensus  of 
opinion.  In  giving  or  selling  a  piece  of  soap  to  the  con- 
sumer, it  is  second  nature  for  him  to  smell  it,  and  in  the 
great  majority  of  cases  his  opinion  is  formed  not  from  any 
quality  the  soap  itself  may  have  during  use,  but  from  the 
odor.  This  only  emphasizes  the  fact  that  the  perfume 
must  be  pleasing,  not  to  one  person,  but  to  the  majority, 
and  many  brands  owe  their  popularity  to  nothing  more 
than  the  enticing  perfume. 

Perfuming  of  soap  is  closely  allied  to  the  soap  making 
industry,  but  as  stated  a  branch  in  itself.  It  is,  therefore, 
not  our  purpose  to  give  numerous  formulae  of  how  to 
perfume  a  soap,  but  rather  to  advise  to  go  for  information 
to  some  one  who  thoroughly  understands  the  character- 
istics of  the  numerous  essential  oils  and  synthetics  and  give 
positive  information  for  the  particular  odor  desired.  Un- 
der no  circumstances  is  it  advisable  to  purchase  a  perfume 
already  compounded,  but  since  all  perfumes  are  a  blend  of 
several  or  many  essential  oils  and  synthetics,  it  is  a  more 
positive  assurance  of  obtaining  what  is  desired,  by  pur- 
chasing the  straight  oils  and  blending  or  mixing  them  as 
one  desires. 

The  perfume  is  added  to  a  milled  soap  just  before  the 
milling    process    in    the    proper    proportion    per    hundred 
pounds  of  soap.     In  cold  made  or  unmilled  soaps  it  is 
74 


CLASSIFICATION    OF    SOAPS 

added  in  the  crutcher  while  the  soap  is  still  hot  By  this 
method,  of  course,  a  proportion  of  the  perfume  is  lost  due 
to  its  being  more  or  less  volatile. 

COLORING    SOAP. 

While  much  toilet  soap  is  white  or  natural  in  color, 
many  soaps  are  also  artificially  colored.  The  soap  colors 
used  for  this  purpose  are  mostly  aniline  dyestuffs.  The 
price  of  these  dyestuffs  is  no  criterion  as  to  their  quality, 
as  the  price  is  usually  regulated  by  the  addition  of  some 
inert,  water  soluble  substance  like  common  salt  or  sugar. 

The  main  properties  that  a  dyestuff  suitable  for  produc- 
ing a  colored  soap  should  have  are  fastness  to  light  and 
to  alkali.  They  should  further  be  of  such  a  type  that  the 
color  does  not  come  'off  and  stain  a  wash  cloth  or  the 
hands  when  the  soap  is  used  and  should  be  soluble  in 
water.  Under  no  circumstances  is  it  advisable  to  add 
these  in  such  a  quantity  that  the  lather  produced  in  the 
soap  is  colored.  It  is  customary  to  first  dissolve  the 
dye  in  hot  w,ater  as  a  standardized  solution.  This  can 
then  be  measured  out  in  a  graduate  and  added  to  the  soap 
the  same  time  as  the  perfume  is  put  in.  About  one  part 
of  color  to  fifty  parts  of  water  is  the  propor  proportion 
to  obtain  a  perfect  solution,  though  this  is  by  no  means 
fixed.  In  making  up  a  solution  thus  it  is  an  improvement 
to  add  to  the  same  about  one-half  of  one  per  cent  of  an 
alkali  either  as  the  hydroxide  or  carbonate.  Then,  if  there 
is  any  possibility  of  change  of  color  due  to  alkalinity  of 
the  soap,  it  will  exhibit  itself  before  the  color  is  added. 

A  particularly  difficult  shade  to  obtain  is  a  purple,  as 
there  is  up  to  the  present  time  no  purplish  aniline  color 
known  which  is  fast  to  light.  Very  good  results  in  soap 
may  be  obtained  by  mixing  a  fast  blue,  as  ultramarine  or 
cobalt  blue,  with  a  red  as  rhodamine  or  cosine. 

75 


SOAP-MAKING    MANUAL  t 

Inasmuch  as  the  colors  for  soap  have  been  carefully 
tested  by  most  of  the  dyestuff  manufacturers,  and  their 
information,  usually  reliable,  is  open  to  any  one  desiring 
to  know  about  a  color  for  soap,  it  is  better  to  depend  upon 
their  experience  with  colors  after  having  satisfied  one's 
self  that  a  color  is  what  it  is  represented  for  a  particular 
shade,  than  to  experiment  with  the  numerous  colors  one's 
self. 

MEDICINAL    SOAPS. 

Soap  is  often  used  for  the  conveyance  of  various 
medicants,  antiseptics  or  other  material  presumably 
beneficial  for  treatment  of  skin  diseases.  While  soap 
is  an  ideal  medium  for  the  carrying  of  such  materials, 
it  is  an  unfortunate  condition  that  when  incorporated 
with  the  soap,  all  but  a  very  few  of  the  numerous  sub- 
stances thus  employed  lose  their  medicinal  properties 
and  effectiveness  for  curing  skin  disorders,  as  well  as 
any  antiseptic  value  the  substance  may  have.  Soap 
is  of  such  a  nature  chemically  that  many  of  the  sub- 
stances used  for  skin  troubles  are  either  entirely  de- 
composed or  altered  to  such  an  extent  so  as  to  impair 
their  therapeutic  value.  Thus  many  of  the  claims  made 
for  various  medicated  soaps  fall  flat,  and  really  have 
no  more  antiseptic  or  therapeutic  merit  than  ordinary 
soap  which  in  itself  has  certain  germicidal  and  cleaning 
value. 

In  medicating  a  soap  the  material  used  for  this  pur- 
pose is  usually  added  at  the  mill.  A  tallow  and  cocoanut 
oil  base  is  best  adapted  for  a  soap  of  this  type.  The 
public  have  been  educated  more  or  less  to  the  use  of 
colored  soap  to  accentuate  its  medicinal  value,  and  green 
is  undoubtedly  the  most  popular  shade.  This  inference, 
however,  is  by  no  means  true  for  all  soaps  of  this 

76 


CLASSIFICATION    OF    SOAPS 

character.     Possibly  the  best  method  of  arranging  these 
soaps  is  briefly  to  outline  some  medicinal  soaps. 

SULPHUR    SOAPS. 

The  best  known  sulphur  soaps  contain  anywhere  from 
one  to  20  per  cent,  of  flowers  of  sulphur.  Other  soaps 
contain  either  organic  or  inorganic  sulphur  compounds. 

TAR  SOAP. 

The  tar  used  in  the  manufacturing  of  tar  soap  is  ob- 
tained by  the  destructive  distillation  of  wood,  the  pine 
tar  being  the  most  extensively  employed.  While  the 
different  wood  tars  contain  numerous  aromatic  com- 
pounds, such  as  phenols,  phenyl  oxides,  terpenes  and 
organic  acids,  these  are  present  in  such  a  slight  pro- 
portion so  as  to  render  their  effectiveness  practically 
useless.  It  has,  therefore,  been  tried  to  use  these 
various  compounds  contained  in  the  tar  themselves  to 
make  tar  soap  really  effective,  yet  tar  is  so  cheap  a 
substance  that  it  is  usually  the  substance  used  for 
medicating  a  tar  soap.  About  10  per  cent,  of  tar  is 
usually  added  to  the  soap  with  2  ounces  of  lamp  black 
per  hundred  pounds  of  soap. 

SOAPS    CONTAINING    PHENOLS. 

Phenol  (Carbolic  Acid)  is  most  extensively  used  in 
soaps  of  this  kind,  which  are  called  carbolic  soaps. 
Carbolic  soaps  are  generally  colored  green  and  contain 
from  1  to  5  per  cent,  phenol  crystals. 

The  cresols  are  also  extensively  used  for  making 
soaps  named  carbolic.  These  substances  impart  more 
odor  to  the  soap  and  really  have  more  disinfecting 
powers  than  phenol  when  incorporated  with  soap. 

Other  soaps,  containing  the  phenol  group,  which  are 
well  known  are  resorcinol  soap,  salol  soap,  thymol  soap, 

77 


SOAP-MAKING    MANUAL 

naphthol  soap,  etc.  From  one  to  five  per  cent  of  the 
compound  after  which  the  soap  is  named  is  usually 
incorporated  with  the  soap. 

PEROXIDE  SOAP. 

Hydrogen  peroxide  in  itself  is  an  excellent  disin- 
fectant. It  loses  all  its  medicinal  value,  however,  when 
added  to  the  soap.  To  overcome  this  objection  various 
metallic  peroxides  are  added  to  the  soap,  as  sodium 
peroxide,  zinc  peroxide  and  barium  peroxide.  These 
generate  hydrogen  peroxide  by  the  addition  of  water. 
Sodium  perborate  is  also  used  in  peroxide  soaps,  as  this 
substance  is  decomposed  by  water  into  hydrogen  per- 
oxide and  sodium  metaborate. 

MERCURY     SOAPS. 

Mercuric  chloride  (corrosive  sublimate)  is  most  ex- 
tensively used  for  the  production  of  mercury  soaps. 
Because  of  its  extremely  poisonous  properties  care 
should  be  taken  in  using  it.  Since  it  really  eventually 
loses  any  antiseptic  value  in  the  soap  through  forming 
an  insoluble  mercury  soap  it  might  better  be  omitted 
entirely. 

LESS   IMPORTANT    MEDICINAL    SOAPS. 

While  the  above  mentioned  soaps  are  probably  the 
best  known  medicated  soaps,  there  are  numerous  other 
soaps  which  may  be  classed  under  these  kinds  of  soaps. 
Thus  we  have  cold  cream  soap,  which  can  be  made  by 
adding  Russian  Mineral  Oil,  1  to  5  per  cent.,  to  the 
soap;  witch  hazel  soap,  made  by  the  addition  of  extract 
of  witch  hazel ;  iodine  soap,  made  by  adding  iodine  or 
iodoform;  formaldehyde  soap,  made  by  adding  for- 
maldehyde; tannin  soaps,  made  by  adding  tannin.  In 
fact,  there  have  been  incorporated  in  soap  so  great  a 

78 


CLASSIFICATION     OF     SOAPS 

number    of    substances    that    the    list    might    be    greatly 
enlarged. 

Medicated  soaps  are  not  only  used  in  solid  form,  but 
in  powder,  paste  and  liquid  soap  as  well.  The  only 
difference  in  a  soap  like  those  just  referred  to  is  that 
the  medicant  is  incorporated  with  these  forms  of  soaps 
as  convenience  directs. 

CASTILE   SOAP. 

A  pure  castile  soap  should  be  made  from  olive  oil. 
This,  however,  is  not  always  the  case,  as  a  number  of 
oils  as  well  as  tallow  are  used  to  adulterate  this  oil  to 
cheapen  it,  and  there  are  even  some  soaps  called  castile 
which  contain  no  olive  oil  at  all.  Most  of  the  pure 
castile  soap  used  in  this  country  is  imported,  as  it  is  a 
difficult  matter  for  the  American  manufacturer  to  com- 
pete with  the  pure  imported  castile  soap,  since  both 
labor  and  oil  itself  are  so  much  cheaper  in  the  vicinities 
of  Europe  where  this  oil  i's  produced,  that  this  advantage 
is  more  than  compensated  by  the  carrying  and  custom 
charges  by  importing  the  castile  soap. 

Castile  soap  may  be  made  either  by  the  full  boiled  or 
cold  process.  There  are  numerous  grades  of  olive  oil, 
and  those  used  for  soap  making  are  denatured  to  lower 
the  duty  charges.  Olive  oil  makes  a  hard  white  soap, 
usually  sold  in  bars,  and  olive  oil  foots  a  green  soap, 
due  to  the  coloring  matter  contained  in  this  oil. 

To  make  a  boiled  castile  soap,  a  composition  of  10 
per  cent.  Cochin  cocoanut  oil  and  90  per  cent,  olive  oil 
may  be  used.  To  cheapen  this,  peanut  oil  (Arachis  oil) 
may  entirely  replace  the  olive  oil,  or  about  20  per  cent. 
of  corn  or  soya  bean  oil  may  be  added.  The  oils  are 
saponified  as  usual  in  making  a  settled  soap  and  to 
prevent  rancidity  the  soap  is  boiled  near  the  finish  for 

79 


SOAP-MAKING     MANUAL 

some  time  in  the  closed  state  with  sufficient  excess  of 
alkali  to  give  it  a  sharp  taste,  then  grained  with  lye, 
the  lye  drawn  off,  closed  with  water  and  then  grained 
with  salt.  This  process  is  repeated  until  the  desired 
strength  is  reached.  The  last  graining  should  not  be 
too  great,  and  on  the  last  change  the  soap  should  not 
be  thinned  out,  as  it  will  contain  too  great  a  quantity  of 
water  when  slabbed. 

In  making  a  cold  castile  soap  the  usual  method  is 
pursued  as  already  directed  under  cold  made  soap. 
When  the  soap  is  taken  from  the  crutcher  it  is  ad- 
visable, however,  to  keep  the  soap  in  the  frame  well 
covered  to  assure  complete  saponification.  Some  manu- 
facturers use  very  small  frames  which  are  placed  into 
compartments,  well  insulated  to  retain  heat.  Several 
formulae  for  cold  made  castile  soaps,  follow.  It  may 
be  noted  that  some  of  these  contain  practically  no  olive  oil. 

I 

Olive  oil    2030 

Palm  kernel   674 

Soda  lye,  35  per  cent.  B 1506 

II 

Olive   oil    2030 

Cochin  cocoanut  oil  674 

Soda  lye,  36  per  cent.  B 1523 

Sodium  Silicate   82 

III 

Palm  kernel  oil  1578 

Tallow    940 

Olive  oil    7 

Sodium  silicate,  20  per  cent.  B 190 

Soda  lye,  36  per  cent.  B 1507 

80 


CLASSIFICATION     OF     SOAPS 

IV 

Olive  oil   (yellow) 1000 

Soda  lye,  37  per  cent.  B 500 


Olive  oil 90 

or 
Palm  kernel 


Cochin  or  cocoanut  oil    ' 

Lye,  37  per  cent.  B 51 

If  any  of  the  soaps  containing  a  high  proportion  of 
cocoanut  oil  are  boiled  the  soap  will  float.  It  is  there- 
fore necessary  to  keep  the  temperature  as  low  as 
possible. 

ESCHWEGER   SOAP    (BLUE    MOTTLED). 

Eschweger  soap  is  a  colored  mottled  or  marbled  soap 
made  to  a  very  slight  extent  in  this  country.  Inasmuch 
as  it  has  been  introduced  to  the  export  trade,  it  is  made 
for  this  purpose  by  some  manufacturers.  A  high  per- 
centage of  cocoanut  oil  is  usually  used  together  with 
tallow  and  grease.  About  one-third  of  each  is  a  typical 
formula.  In  a  soap  of  this  character  the  fact  that 
cocoanut  oil  soap  takes  up  a  large  quantity  of  water 
and  salts  of  various  kinds  and  is  difficult  to  salt  out  is 
made  use  of.  The  tallow  and  grease  are  first  saponified 
as  usual,  then  the  cocoanut  oil  is  pumped  and  saponified. 
When  the  saponification  is  nearly  completed  either  sili- 
cate or  carbonate  of  soda  or  common  salt  are  added  to 
make  the  soap  "short"  so  as  to  form  the  mottle.  The 
finishing  of  a  soap  of  this  type  can  only  be  gained  by 
practice  and  it  is  rather  difficult  to  explain  the  exact 
appearance  of  the  kettle  at  this  stage.  The  surface  of 
the  soap  should  be  bright  and  lustrous  with  the  steam 

81 


SOAP-MAKING     MANUAL 

escaping  in  numerous  places  in  rose-like  formation.  A 
sample  on  the  trowel  should  have  a  slight  sharpness 
to  the  tongue  and  be  plastic.  When  the  soap  slides 
from  the  trowel  it  should  break  short.  When  the  soap 
has  reached  this  stage  the  desired  coloring  matter,  usually 
ultramarine,  is  added  to  the  soap  either  in  the  kettle  or 
crutcher  and  the  soap  framed.  The  yield  is  200-215  pounds 
per  hundred  pounds  of  stock. 

Several  modifications  of  this  general  method  for 
Eschweger  soap  are  used  by  adopting  the  half  boiled 
or  cold  process. 

TRANSPARENT  SOAP. 

Transparent  soap  is  really  not  a  most  desirable  soap  for 
toilet  purposes,  as  it  contains  an  excess  of  free  alkali.  It 
has,  nevertheless,  met  with  public  approval  because  of  the 
fact  it  is  novel  in  being  transparent.  Except  for  this  fact 
very  little  merit  can  be  claimed  for  a  soap  of  this  kind. 

The  transparency  of  soap  is  generally  due  to  the  presence 
of  alcohol,  sugar  or  glycerine  in  the  soap  when  it  is  made 
It  is  very  essential  in  a  soap  of  this  character,  where  light- 
ness and  clearness  of  color  are  desired,  that  the  material 
for  making  the  soap  be  carefully  selected  as  to  color  and 
purity.  The  perfumes  also  play  an  important  part  in  the 
color  of  the  soap  and  many  of  the  tinctures,  balsams  and 
infusions  used  in  perfuming  soap  may  eventually  cause 
trouble  by  spotting.  If  the  soap  is  artificially  colored,  which 
is  almost  always  the  case,  the  dyestuffs  used  for  this 
purpose  should  have  careful  attention  and  only  those  should 
be  used  which  are  known  to  resist  the  action  of  alkalis. 
Where  rosin  is  used  this  product  must  be  of  the  better 
grade.  Distilled  water  is  always  preferable  for  use  in  trans- 
parent soap.  The  government  permits  the  use  of  a  specially 
denatured  alcohol.  This  alcohol  is  not  taxed  and  consists  of 
grain  (ethyl)  alcohol  denatured  with  5  per  cent,  wood 

82 


CLASSIFICATION     OF    SOAPS 

(methyl)  alcohol.  Some  soapmakers  prefer  to  use  a  more 
expensive  refined  methyl  alcohol,  but  outside  of  adding 
to  the  cost  of  the  soap,  there  is  no  particular  advantage. 
The  glycerine  should  be  chemically  pure.  As  to  the  oils 
and  fats  these  should  be  low  in  acid  and  of  good  color. 
Under  no  circumstances  should  the  crutcher  or  kettle  in 
which  the  soap  is  made  be  rusty  or  unclean  in  any  way. 
For  a  light  soap  enameled  utensils  are  to  be  preferred. 
To  obtain  transparency  in  soap  the  following  general 
methods  may  be  given. 

1.  Where  the  transparency  is  due  to  sugar. 

2.  Where  alcohol  and  glycerine  produce  transparency. 

3.  Where    (1)    or    (2)    is   supplemented   by   the   use   of 
castor  oil. 

4.  Where  transparency  depends  upon  the  percentage  of 
fatty  acid  in  a  soap  and  the  number  of  times  the  soap  is 
milled. 

Under  the  first  method  at  least  25  per  cent,  of  the  charge 
should  be  cocoanut  oil,  the  other  constituent  being  tallow 
or  any  fat  or  oil  capable  of  giving  a  sufficiently  hard  soap. 
The  soap  is  boiled  and  finished  as  usual,  then  run  to  the 
crutcher  to  be  mixed  with  a  strong  cane  sugar  solution, 
containing  10-20  per  cent,  sugar  of  the  weight  of  the  soap. 
The  sugar  is  dissolved  in  its  own  weight  of  water  and  the 
solution  heated  to  175  degs.  F.  before  being  very  slowly 
added  to  the  soap.  As  the  water  evaporates,  soaps  of  this 
type  show  spots  due  to  the  sugar  thus  being  thrown  out 
of  solution. 

Transparent  soap  made  under  the  second  method  may 
be  saponified  as  usual  and  consist  of  any  good  toilet  base. 
The  soap  is  run  to  the  crutcher  and  mixed  with  95  per  cent, 
alcohol  in  the  proportion  of  one  part  alcohol  to  two  parts 
of  fatty  acid  contained  in  the  soap  together  with  glycerine 
in  the  same -proportion. 

83 


SOAP-MAKING    MANUAL 

By  the  third  method  castor  oil  alone  may  be  used  to 
make  the  soap  or  added  to  any  of  the  above  bases  up  to 
33j/j  per  cent,  of  the  charge.  If  castor  oil  only  is  used, 
but  2  per  cent,  or  3  per  cent,  of  sugar  is  required. 

In  the  last  method  a  combination  of  80  per  cent  tallow, 
very  low-  in  free  acid,  20  per  cent,  cocoanut  oil  and  5  per 
cent.  W.  W.  rosin  is  a  suitable  charge.  The  saponification 
and  finishing  is  carried  out  as  with  a  full  boiled  soap. 
The  soap  is  then  placed  into  a  jacketed  vessel,  provided 
with  dry-steam  coils,  by  which  the  excess  water  is 
evaporated  from  the  soap  until  it  contains  73  per  cent,  fatty 
acids.  When  the  thick  mass  reaches  this  stage  it  is  framed 
and  when  cool  is  suitable  for  obtaining  a  semi  transparency 
which  now  depends  upon  the  number  of  times  the  soap  is 
milled,  it  being,  of  course,  inferred  that  no  solid  matter 
of  any  sort  be  added  to  the  soap. 

COLD  MADE  TRANSPARENT  SOAP. 

While  transparent  soaps  may  be  made  by  the  above 
general  methods  they  are  usually  made  by  the  semi-boiled 
or  cold  process.  By  this  process  a  more  satisfactory  soap 
is  obtained  and  it  is  more  simple  to  carry  out.  A  detailed 
description  of  this  method  is  best  and  most  easily  given 
by  using  a  typical  formula. 

Charge : 

Tallow   193^  Ibs. 

Cochin  Cocoanut  Oil 
Castor  Oil 

Soda  Ash 7 

Soda  Lye,  36  degs.  B 256 

Sugar  (Cane)    198 

Alcohol 126 

Water   (Distilled)    80- 

84 


CLASSIFICATION     OF    SOAPS 

To  proceed,  first  place  into  a  crutcher  or  jacketed  kettle 
the  oils  and  fat  and  heat  to  140  degs.  F.  Then  add  the 
soda  ash  dissolved  in  about  30  pounds  of  the  water,  after 
which  the  lye  is  added  and  the  mass  stirred  until  a  finger 
or  stick  run  over  the  surface  leaves  an  imprint.  Where 
the  soap  has  reached  this  stage,  it  is  well  covered  and 
allowed  to  stand  about  two  hours  or  until  it  bulges  in  the 
center,  after  which  the  rest  of  the  water  which  should 
contain  no  lime  or  other  mineral  substance  and  which  is 
preferably  distilled  water,  is  added.  The  sugar  is  then 
slowly  shoveled  in  while  the  mass  is  stirring  and  finally 
the  alcohol  is  poured  in.  The  heat  is  then  increased  to 
160  degs.  F.  by  dry  steam  and  the  soap  crutched  until 
dissolved.  Under  no  circumstances  should  any  soap  be 
allowed  to  remain  above  the  surface  of  the  mass  on  the 
sides  of  the  mixer.  This  crutching  operation  consumes 
about  one  hour,  and  when  finished  the  soap  should  stand 
in  the  vessel  about  half  an  hour  when  a  small  sample  is 
taken  out  to  cool.  This  sample  should  be  clear  and  show 
an  excess  of  alkali.  If  it  is  not  clear  more  alcohol  ifr 
added,  if  not  of  sufficient  strength  more  lye  put  in  until  the 
desired  condition  is  reached.  The  perfume  and  color  are 
now  added. 

The  soap  is  then  framed  and  allowed  to  set  after  which 
it  is  cut,  allowed  to  dry  slightly  and  then  pressed.  To 
obtain  a  polished  cake  transparent  soaps  are  often  planed 
before  pressing  and  after  pressing  polished  with  a  soft  cloth, 
dampened  with  alcohol.  Instead  of  framing  this  soap,  it  is 
sometimes  "tubed,"  that  is  to  say,  the  soap  from  the  crutcher 
is  run  into  specially  constructed  tubes  of  a  shape  near 
that  of  the  desired  cake  and  allowed  to  cool,  after  which 
it  is  cut  and  pressed.  All  scraps  arc  returned  to  the 
crutcher,  but  in  so  doing  the  soap  is  slightly  darkened  in 
color.  It  is  advisable  to  expose  a  finished  cake  of  trans- 

85 


SOAP-MAKING     MANUAL 

parent  soap  to  the  air  for  some  time  as  by  so  doing  it 
becomes  clearer. 

Other  formulae  for  cold  made  transparent  soaps  made 
as  just  outlined  follow: 

I. 

Bleached  Tallow    134  Ibs. 

Cochin  Cocoanut  Oil  88    " 

Castor  Oil    20    " 

W.    W.    Rosin    7    " 

Cane   Sugar    64    " 

Water  32    " 

Glycerine  34    " 

Soda  Lye,  38  degs.   B 135    " 

Alcohol   16  gal. 

II. 

Tallow    211      Ibs. 

Cochin  Cocoanut  Oil  185        " 

Castor   Oil    97^    " 

Soda  Ash    Sl/2    " 

Water    106 

Soda  Lye,  38  degs.  B 279 

Sugar    216 

Alcohol    137 

III. 

Castor    Oil 60      Ibs. 

Cochin  Cocoanut  Oil  195 

Tallow    120 

Alcohol    115 

Sugar    90 

Water    53 

Glycerine  53 

Soda  Lye,  38  degs.  B 205^ 

86 


CLASSIFICATION    OF    SOAPS 

IV. 

Tallow    100      Ibs. 

Cochin  Cocoanut  Oil 100 

Castor   Oil    60 

Glycerine   20        " 

Rosin,  W.  W 20 

Sugar    40 

Water  50 

Soda  Lye,  36  degs.   B 164 

Alcohol    8      gal. 

V. 

Tallow  174  Ibs. 

Cocoanut  Oil  114    " 

Soda  Lye,  38  degs.  B 170    " 

Sugar    80    " 

Water  72    " 

Alcohol    16  gal. 

Rosin  may  be  added  in  this  formula  up  to  20  per  cent, 
of  fats  used  and  the  tallow  cut  down  correspondingly. 

SHAVING    SOAPS. 

The  requirements  of  a  shaving  soap  are  somewhat 
different  than  those  of  other  soaps.  To  be  a  good  shaving 
soap  the  lather  produced  therefrom  must  be  heavy,  creamy, 
but  not  gummy,  and  remain  moist  when  formed  on  the 
face.  The  soap  itself  should  be  of  a  soft  consistency  so 
as  to  readily  adhere  to  the  face  when  used  in  stick  form. 
It  should  furthermore  be  neutral  or  nearly  so  to  prevent 
the  alkali  from  smarting  during  shaving. 

Shaving  soap  is  made  in  the  form  of  a  stick,  and  a  tablet 
for  use  in  the  shaving  mug.  Some  shavers  prefer  to  have 
the  soap  as  a  powder  or  cream,  which  are  claimed  to  be 
more  convenient  methods  of  shaving.  While  a  liquid 
shaving  soap  is  not  as  well  known  because  it  has  not  yet 
87 


SOAP-MAKING    MANUAL 

become  popular,  some  soap  for  shaving  is  made  in  this 
form. 

Formerly  shaving  soap  was  extensively  made  from  a 
charge  of  about  80  parts  tallow  and  20  parts  cocoanut  oil 
as  a.  boiled  settled  soap,  but  either  making  the  strengthen- 
ing change  with  potash  lye  or  using  potash  lye  in  saponify- 
ing the  stock  and  graining  with  salt.  Soaps  for  shaving 
made  in  this  manner  are  very  unsatisfactory,  as  they  do 
not  produce  a  sufficiently  thick  or  lasting  lather  and  dis- 
color very  materially  upon  ageing.  Potassium  stearate 
forms  an  ideal  lather  for  shaving,  but  readily  hardens  and 
hence  needs  some  of  the  softer  oils,  or  glycerine  incor- 
porated with  it  to  form  a  satisfactory  soap  for  shaving. 

The  selection  of  materials  for  making  a  shaving  soap 
is  important.  The  tallow  used  should  be  white  and  of 
high  titer.  Cochin  cocoanut  oil  is  to  be  preferred  to  the 
other  kinds,  and  the  alkalis  should  be  the  best  for  tech- 
nical use  that  can  be  purchased — 76  per  cent,  caustic  soda 
and  88-92  per  cent,  caustic  potash  are  suitable.  By  the  use 
of  stearic  acid  it  is  a  simple  matter  to  reach  the  neutral 
point  which  can  be  carefully  approximated. 

The  following  are  shaving  soap  formulae  which  have 
been  found  to  give  good  satisfaction: 

I.  Ibs. 

Tallow 360 

Stearic  acid    40 

Soda  lye,  41°  B -. . .  147 

Potash  lye,  34°   B 87 

Water    32 

Gum  tragacanth    1 

II.  Ibs. 

Tallow    282 

Cocoanut  oil    60 

88 


CLASSIFICATION    OF    SOAPS 

Stearic  acid   50 

Bayberry  wax    18 

Soda  lye,  41°  B 147 

Potash  lye,  34°   B 90 

Water    32 

III.  Ibs. 

Tallow   400 

Cocoanut  oil    176 

Stearic  acid   415 

Caustic  soda,  40°  B 182 

Caustic  potash,  38°  B 108 

To  proceed,  first  run  into  the  crutcher  the  tallow,  cocoa- 
nut  oil  and  bayberry  wax  when  used,  and  bring  the  tem- 
perature of  the  mass  up  to  140°-160°  F.  by  dry  steam.  Then 
add  the  caustic  soda  lye  and  keep  on  heat  with  occasional 
mixing  until  it  is  all  taken  up.  When  this  stage  is  reached 
gradually  add  all  but  about  5  per  cent,  of  the  potash  lye, 
and  complete  the  saponification.  This  point  having  been 
reached,  the  heat  is  turned  off;  the  crutcher  is  run  and 
the  stearic  acid,  previously  melted  by  dry  steam  in  a  lead- 
lined  or  enameled  vessel,  is  run  in  in  a  continuous  stream 
and  the  crutching  continued  for  fifteen  minutes  to  half 
an  hour.  Samples  are  taken  at  this  time,  cooled  and 
tested  by  alcoholic  phenolphthalein  solution.  If  too  alkaline 
more  stearic  acid  is  added,  if  too  acid  more  potash  lye 
from  that  previously  reserved.  After  each  addition  of  lye 
or  stearic  acid  the  mass  is  crutched  from  10  to  15  minutes 
longer,  another  sample  is  taken,  cooled  and  again  tested. 
When  the  phenolphthalein  shows  a  very  light  pink  after 
several  minutes,  the  soap  is  practically  neutral,  although 
at  this  point  one  can  better  judge  by  dissolving  a  sample 
in  hot  neutralized  alcohol  made  by  putting  into  the  alcohol 
a  few  drops  of  phenolphthalein,  and  then  adding  weak 

89 


SOAP-MAKING     MANUAL 

alkali  drop  by  drop  from  a  burette  until  a  slight  pink,  not 
yellow,  tint  is  obtained,  and  noting  the  color  of  the  solu- 
tion. The  solution  should  show  a  very  light  pink  when 
the  soap  is  properly  neutralized.  When  this  stage  is  ar- 
rived at  the  gum  tragacanth,  previously  softened  in  water, 
is  crutched  in  if  it  is  to  be  added.  The  soap  is  then 
framed,  stripped  in  three  or  four  days,  dried  and  milled. 
The  formulae  as  given  are  for  shaving  sticks,  and  do 
not  readily  press  unless  thoroughly  dried.  A  more  satis- 
factory result  is  obtained  by  adding  at  the  mill  25  per 
cent,  of  white  tallow  base  to  obtain  a  satisfactory  mug 
soap. 

SHAVING    POWDER. 

Shaving  powder  differs  from  the  soaps  just  described 
in  being  pulverized,  usually  adding  up  to  5  per  cent,  starch 
to  prevent  caking.  Any  of  the  above  soaps,  dried  bone 
dry,  with  or  without  the  addition  of  tallow  base  make  a 
satisfactory  powder  for  shaving. 

SHAVING   CREAM. 

Shaving  cream  is  now  a  very  popular  shaving  medium 
due  to  the  rapidity  and  convenience  with  which  one  can 
shave  by  the  use  of  this  product.  Formerly  shaving 
cream  was  made  from  the  liquid  oils  like  olive  oil  and  a 
soft  fat  like  lard,  together  with  cocoanut  oil.  Now,  how- 
ever, most  of  the  popular  shaving  creams  are  made  from 
stearic  acid  and  cocoanut  oil,  as  a  far  superior  product  is 
obtained  by  the  use  of  these  substances.  By  using  these  a 
more  satisfactory  cream  is  obtained,  and  it  is  far  more 
convenient  to  make.  The  lather  also  produced  therefrom 
is  more  suitable  for  shaving,  being  thick,  creamy  and  re- 
maining moist. 

A  few  typical  formulae  for  shaving  creams  of  this  type 
are  as  follows: 

90 


CLASSIFICATION     OF    SOAPS 

I-  Ibs. 

Cochin  cocoanut  oil 26 

Stearic  acid   165 

Caustic  potash  lye,  50°  B 69 

Glycerine  C.  P 76 

Water    38 

n.  ibs. 

Cochin  cocoanut   oil 18 

Stearic  acid   73 

Caustic  potash  lye,  39°  B 54 

Glycerine    33 

Water    27 

HI.  Ibs. 

Cochin  cocoanut  oil 18 

Stearic  acid   73 

Caustic  potash  lye,  39°  B 54 

Glycerine    20 

Water   40 

and  Ibs. 

Stearic  acid   60 

Glycerine  C.  P 85 

Water    165 

Sodium  carbonate    50 

Borax    1 

To  make  a  shaving  cream  by  Formula  I  or  II,  the  cocoa- 
nut  oil  and  glycerine  are  first  put  into  a  suitable  mixing 

apparatus  or  crutcher,  and  heated  to  120°  F.  A  part  or 
all  the  potash   lye   is   then   added   and   the   cocoanut   oi! 

91 


SOAP-MAKING     MANUAL 

saponified.  The  rest  of  the  potash  lye  and  the  water  are 
then  added,  and  with  the  mixer  running  the  stearic  acid, 
previously  melted  in  a  lead-lined  or  enameled  vessel,  is 
then  poured  in  in  a  stream  and  the  mass  stirred  until 
smooth,  care  being  exercised  not  to  aerate  it  too  much. 
The  cream  is  then  tested  for  alkalinity,  the  best  method 
being  by  that  described  under  shaving  soap,  in  which 
the  sample  is  dissolved  in  alcohol.  Because  of  the  large 
quantity  of  water  present,  phenolphthalein  is  unsatisfac- 
tory, as  dissociation  of  the  soap  may  show  a  pink  indica- 
tion in  spite  of  the  fact  the  mass  is  on  the  acid  side.  For 
a  quick  method  of  testing  the  bite  on  the  tongue  is  a 
satisfactory  criterion.  If  a  cooled  sample  bites  the  tongue 
more  stearic  acid  is  added  until  there  is  a  3%  excess  of  this. 
When  the  proper  neutralization  has  taken  place  the  cream 
is  perfumed  and  framed  in  a  special  frame,  or  it  may  be 
allowed  to  cool  in  the  mixer  and  perfumed  the  next  day. 
When  cool  the  cream  is  strained,  or  put  through  an  oint- 
ment mill,  after  which  it  is  ready  to  fill  into  tubes. 

The  procedure  for  the  first  part  of  Formula  III  is  the 
same  as  that  just  given.  The  second  part  of  the  formula 
is  made  the  same  as  a  vanishing  cream  for  toilet  purposes. 
To  make  this,  first  melt  the  stearic  acid  as  already  directed. 
Dissolve  the  sodium  carbonate  and  borax  in  water  and 
when  dissolved  add  the  glycerine  and  stir.  Then  heat 
this  solution  to  about  100° -120°  F.  and  while  stirring  in 
a  suitable  mixing  machine  into  which  this  solution  has 
been  poured  after  being  heated,  or  better  still  in  which 
it  has  been  heated  by  dry  steam,  add  the  stearic  acid. 
Continue  mixing  until  smooth  and  then  allow  to  cool,  or 
run  into  frames  to  cool. 

When  the  shaving  cream  and  vanishing  cream  are  both 
cool,  they  are  mixed  in  the  proportion  of  one  of  the 
former  to  two  of  the  latter.  It  is  claimed  that  in  thus 

92 


CLASSIFICATION     OF    SOAPS 

making  a  shaving  cream  a  smoother  product  is  ob- 
tained, although  it  may  be  said  that  the  vanishing  cream 
is  merely  a  soft  soap  and  the  ultimate  result  is  the  same 
as  though  the  various  ingredients  were  added  in  one 
operation,  rather  than  making  two  separate  products  and 
then  mixing  them,  thereby  considerably  increasing  the  cost 
of  manufacture. 

PUMICE  OR  SAND   SOAPS. 

Pumice  and  sand  are  at  times  added  to  soap  to  aid  in 
the  removal  of  dirt  in  cleansing  the  hands.  In  some  cases 
these  soaps  are  made  in  the  form  of  a  cake,  in  others 
they  are  sold  in  cans  in  the  form  of  a  paste. 

A  hand  paste  is  usually  made  by  merely  dissolving 
ordinary  tallow  base  in  two  or  three  times  its  weight  of 
hot  water  and  mixing  in  the  desired  quantity  of  pumice 
or  sand  and  in  some  instances  adding  a  little  glycerine 
to  keep  it  soft  or  a  solvent  of  some  kind  for  grease.  It 
may  also  be  made  by  directly  incorporating  any  of  these 
in  a  potash  soap. 

A  cold  made  or  semi-boiled  cocoanut  or  palm  kernel  oil 
soap  is  the  base  used  to  add  the  pumice  or  sand  to  in 
making  a  cake  soap  of  this  sort.  The  following  formulae 
serve  as  a  guide  for  these  soaps. 

I. 

Palm  Kernel  or  Ceylon  Cocoanut  Oil. . . .  705  Ibs. 

Pumice    (Powdered)     281     " 

Soda   Lye,   38°    B 378    " 

II. 

Cocoanut  Oil   100  " 

Soda  Lye,  38°  B 55  " 

Water    6  " 

Silver  Sand  (fine) 60  " 

93 


SOAP-MAKING    MANUAL 

To  proceed  place  the  oil  in  a  crutcher  and  heat  to  140* 
F.  Sift  in  the  pumice  and  mix  thoroughly.  The  lye  is 
then  added  which  causes  a  curdling  of  the  grain.  The 
stirring  is  continued  until  the  grain  closes  and  the  soap 
is  smooth,  after  which  the  desired  perfume  is  added  and 
the  soap  dropped  into  a  frame  and  crutched  by  hand. 
When  the  soap  is  set,  it  is  slabbed,  cut  into  cakes,  dried 
slightly  and  pressed. 

LIQUID    SOAPS. 

Liquid  soaps  are  merely  solutions  of  a  potash  soap, 
usually  cocoanut  oil  soap,  although  corn  oil  is  used  to 
make  a  cheap  soap.  One  of  the  difficulties  encountered 
in  liquid  soap  is  to  keep  it  clear.  At  a  low  temperature 
a  sediment  is  often  formed,  but  this  can  be  overcome  by 
the  use  of  sugar  and  filtering  the  soap  through  a  filter 
press  at  a  low  temperature.  In  order  to  prevent  the  soap 
from  freezing,  it  is  necessary  to  lower  the  freezing  point 
by  the  addition  of  glycerine  or  alcohol. 

To  make  liquid  soap  by  any  of  the  formulae  given 
below,  the  oil  is  first  run  into  a  jacketed  kettle  with  a 
stirring  device,  and  heated  to  about  120°  F.  The  potash 
lye  is  then  added  and  the  oil  saponified.  When  the  saponifi- 
cation  takes  place,  especially  when  cocoanut  oil  is  used, 
the  mass  swells  rapidly  and  may  foam  over  the  sides  of 
the  kettle  unless  water  is  used  to  check  this,  or  a  kettle 
of  about  four  to  five  times  the  capacity  of  the  total  charge 
of  soap  is  used.  When  the  saprfnification  has  occurred, 
the  sugar,  borax  and  glycerine  are  added,  the  water  run 
in  and  the  mixture  stirred  until  the  soap  is  thoroughly 
dissolved.  Heat  aids  materially  in  dissolving  the  soap. 
The  soap  is  then  allowed  to  cool  and  if  color  or  perfume 
is  to  be  added  this  is  stirred  in,  after  which  the  soap  is 
cooled  and  filtered  or  else  run  directly  into  barrels. 

94 


CLASSIFICATION    OF    SOAPS 

Tallow  is  not  suitable  for  making  a  clear  liquid  soap 
since  it  is  too  high  in  stearine  which  when  formed  into 
the  stearate  makes  an  opaque  solution.  The  formulae 
herewith  given  have  been  found  to  give  good  practical 
results. 

I.  Ibs. 

Cocoanut   oil    130 

Caustic  potash  lye,  28°  B. . . . 135 

Sugar   72 

Borax    2 

Water    267 

II.  Ibs. 

Corn   oil    130 

Caustic  potash  lye,  26°   B 135 

Sugar   72 

Borax    2 

Water    267 

HI.  Ibs. 

Cocoanut  oil    100 

Caustic  potash  lye,  28°  B 102 

Glycerine  100 

Sugar   70 

Water    833 

Formulae  I  and  II  contain  about  20  per  cent,  fatty  acids. 
It  is  possible,  of  course,  to  either  increase  or  decrease 
the  percentage  of  fatty  acid  by  varying  the  amount  of 
water.  The  water  used  in  making  liquid  soaps,  of  course, 
should  be  soft,  for  hard  water  forms  insoluble  soaps 
which  precipitate  and  cause  a  sediment. 

95 


SOAP-MAKING    MANUAL 

USE     OF     HARDENED     OILS     IN     TOILET     SOAPS. 

While  the  introduction  of  the  hydrogenation  of  oils  is  a 
decided  advance  in  the  production  of  suitable  cheaper  oils 
for  soap  making,  comparatively  little  hardened  oil  is  em- 
ployed for  soap  making  in  America  up  to  the  present  time. 
In  Europe,  however,  considerable  advance  has  been  made 
by  the  use  of  such  oils  for  manufacturing  soap  therefrom 
and  a  number  of  plants  turn  out  large  quantities  of  hydro- 
genated  oils  for  soap  making  as  well  as  for  edible  purposes. 
Recently  a  company  has  been  formed  in  this  country  for 
hardening  oils  and  it  is  very  probable  that  the  future  will 
see  this  material  extensively  used  in  our  own  country,  as 
these  appear  to  be  the  one  present  hope  of  the  soap  manu- 
facturer as  a  check  on  the  ever  increasing  cost  of  fats  and 
oils  now  used  in  making  soap. 

It  is  an  unfortunate  condition  that  hydrogenated  oils 
produced  abroad  are  sold  under  names  which  give  ab- 
solutely no  indication  as  to  the  oil  which  has  been  hardened. 
The  softer  and  cheaper  oils  like  fish  oil,  linseed  oil,  cotton- 
seed oil,  etc.,  are  generally  hardened  for  soap  manufacture 
to  different  degrees  of  hardness.  While  it  is  impossible  to 
definitely  state  just  what  products  as  Candelite,  Talgol, 
Krutolin  or  several  other  coined  names  of  hardened  oils 
are,  various  investigators  have  experimented  with  them  as 
to  their  adaptability  for  producing  toilet  soaps  and  found 
that  suitable  toilet  soaps  may  be  made  from  them.  While 
many  objections  were  at  first  met  with  concerning  soaps 
made  from  these  products,  as  to  their  unsatisfactory  saponi- 
fication,  the  poor  lathering  quality  of  the  soaps  and  their 
odor  and  consequent  difficulty  in  perfuming,  the  results  of 
most  investigators  along  these  lines  indicate  that  these  in 
many  cases  were  due  to  prejudice  against  or  tinfamiliarity 
with  handling  oils  of  this  type  for  soap  making. 

In  manufacturing  soap  from  hardened  oils  it  is  usually 
96 


CLASSIFICATION     OF     SOAPS 

necessary  to  incorporate  with  the  charge  lard,  tallow,  tallow 
oil  or  some  other  soft  oil  of  this  nature.  Satisfactory  bases 
for  toilet  soaps,  made  as  boiled  settled  soap  by  the  use  of 
Talgol  (undoubtedly  hardened  fish  oil),  are  said  to  be 
made  by  the  formulae*  below. 

I. 

Tallow    45  parts 

Talgol    40      " 

Cocoanut  Oil    15      " 

II. 

Cocoanut   Oil    (Ceylon) 6  " 

Tallow 12  " 

Talgol,  Extra   12  " 

The  method  of  boiling  a  soap  of  this  type  does  not  differ 
materially  from  that  of  making  settled  tallow  soap  base. 
The  soap  itself  has  a  different  odor  than  a  straight  tallow 
base,  but  is  said  to  make  a  very  satisfactory  soap  for 
milling  and  to  be  of  good  appearance. 

Satisfactory  transparent  soaps  are  made  from  the 
hardened  oil  Candelite,  which  replaces  the  tallow  in  trans- 
parent soap  formulae  such  as  have  already  been  given  in 
the  section  under  'Transparent  Soaps."  The  method  of 
manufacturing  a  soap  by  the  use  of  this  product  varies  in 
no  way  from  the  usual  method  employed  for  making  these 
soaps. 

Since  hydrogenated  oils  are  high  in  stearine,  their  use 
in  shaving  soaps  is  a  decided  advantage.  It  has  pre- 
viously been  pointed  out  that  potassium  stearate  forms 
an  ideal  lather  for  shaving,  and  in  the  hydrogenating 
process  the  olein  is  converted  to  stearine.  Thus  a  hardened 


•Seifensieder  Ztg.   (1913),  p.  334  and  338. 

"     (1912),    p.    1229    and    1257. 

97 


SOAP-MAKING     MANUAL 

oil  is  advantageous  in  a  shaving  soap.     As  an  example  of 
a  cold  made  soap  for  shaving  the  following  may  be  taken. t 

Talgol  Extra   50  Ibs. 

Cocoanut  Oil   10    " 

Lard 10    " 

Soda  Lye,  38°  B 20    " 

Potash  Lye,  37°  B 21     " 

This  soap  may  be  made  in  a  crutcher  by  the  method 
generally  used  in  making  soap  by  the  cold  process. 

TEXTILE   SOAPS. 

Soap  is  a  very  important  product  to  every  branch  of  the 
textile  industry.  For  woolen  fabrics  it  is  used  for  scouring, 
fulling  and  throwing  the  wool;  in  the  silk  industry  it  is 
necessary  for  degumming  the  raw  silk,  as  well  as  for  dye- 
ing; in  the  cotton  mills  it  is  used  to  finish  cotton  cloth 
and  to  some  extent  in  bleaching;  it  is,  furthermore,  em- 
ployed in  a  number  of  ways  in  the  manufacture  of  linen. 
Large  quantities  of  soap  are  thus  consumed  in  an  in- 
dustry of  so  great  an  extent  and  the  requirements  neces- 
sitate different  soaps  for  the  different  operations.  We 
will,  therefore,  consider  these  in  detail. 

SCOURING    AND   FULLING    SOAPS    FOR   WOOL. 

The  soaps  used  to  scour  wool  and  for  fulling  the  woven 
cloth  are  usually  made  as  cheaply  as  possible.  They  are, 
however,  generally  pure  soaps,  as  filling  material  such  as 
sodium  silicate  does  not  readily  rinse  out  of  the  wool  and 
if  used  at  all  must  be  added  very  sparingly.  Both  cold 
made  and  boiled  settled  soaps  are  made  for  this  purpose. 
The  soap  is  generally  sold  in  barrels,  hence  is  run  directly 
to  these  from  the  crutcher  or  soap  kettle.  As  cold  made 
soaps  the  following  serve  for  wool  scouring  or  fulling. 

tSeifentieder  Ztg.   (1912),  p.  954. 
98 


CLASSIFICATION     OF    SOAPS 

I. 

Palm  Oil  200  Ibs. 

Bone  Grease 460  " 

Soda  Lye,  36°   B 357  " 

Water  -. 113  " 

Soda  Ash   50  " 

Citronella 2  " 

II. 

Palm    Oil    (Calabar,    unbleached) 155  " 

House  Grease   360  " 

Soda  Lye,  36°  B 324  " 

Water  268  " 

Sodium  Silicate 83  " 

III. 

House  Grease   185  " 

Palm  Oil   (unbleached) 309  " 

Soda  Lye,  36°  B 309  " 

Water  391  " 

Soda  Ash 70  " 

Sodium   Silicate    60  " 

Corn  Starch  10  " 

These  soaps  are  made  in  a  crutcher  by  the  usual  pro- 
cess for  cold-made  soaps,  crutched  until  smooth,  dropped 
into  a  barrel  and  crutched  by  hand  the  next  day  or  just 
before  cooling. 

As  a  settled  soap  for  these  operations  the  following 
charge  is  typical: 

Palm  Oil   34  parts 

Cottonseed    foots    or    its    equivalent    in 

fatty  acids   33 

Rosin   10  " 

House  Grease  23  " 

99 


SOAP-MAKING     MANUAL 

The  method  of  boiling  such  a  soap  is  the  same  as  for 
any  settled  soap  up  to  the  strengthening  change.  When 
this  stage  is  reached,  sufficient  lye  is  added  to  strengthen 
the  kettle  strongly.  It  is  then  boiled  down  with  closed 
steam  on  salt  brine  or  "pickle"  until  a  sample  of  the  lye 
taken  from  the  bottom  stands  at  16° -22°  B.  The  soap  is 
then  run  into  barrels  and  after  standing  therein  for  a  day 
is  hand  crutched  until  cool  to  prevent  streaking  of  the  soap. 

Besides  a  soap  of  this  type  a  settled  tallow  chip  soap  is 
used. 

WOOL  THROWER'S  SOAP. 

Soaps  for  wool  throwing  are  sometimes  made  from 
olive  oil  foots  but  these  are  often  objected  to  because 
of  the  sulphur-like  odor  conveyed  to  the  cloth  due  to  the 
method  by  which  this  oil  is  extracted  with  carbon  disul- 
phide.  A  potash  soap  hardened  somewhat  with  soda  is 
also  used.  As  a  formula  for  a  suitable  soap  of  this  type 
this  may  be  given. 

Olive  Oil  Foots   12  parts 

Corn  Oil   46       " 

House  Grease    20 

Soda  Lye,  36°   B 3       " 

Potassium  Carbonate  (dry) 5^    ' 

Potassium  Hydrate    (solid) 23 

This  soap  is  made  as  a  "run"  soap  by  the  general 
directions  already  given  for  a  soap  thus  made.  The  kettle 
is  boiled  with  open  and  closed  steam,  adding  water  verj 
slowly  and  aiming  to  obtain  a  220-225  per  cent,  yield  or 
fatty  acid  content  of  the  finished  soap  of  46  per  cent. 
When  the  soap  is  finished  a  sample  cooled  on  a  plate  of 
glass  should  be  neither  slippery  or  short,  but  should  string 
slightly.  The  finished  soap  is  run  directly  into  barrels. 

100 


CLASSIFICATION    OF;  SCABS   ; 

A  soap  for  wool  throwing  by  the  semi-boiled  process 
may  be  made  from  olive  oil  foots  in  a  crutcher  thus  : 

Olive  Oil  Foots  .........................     600  Ibs. 

Potash  Lye,  20°  B  ......................     660    " 

The  oil  is  heated  to  180°  F.,  the  lye  added  and  the 
mass  stirred  until  it  bunches,  when  it  is  dropped  into 
barrels. 

WORSTED  FINISHING  SOAPS. 

For  the  finishing  of  worsted  cloth  soaps  high  in  cocoa- 
nut  oil  or  palm  kernel  oil  are  preferred.     These  soaps  are 
finished   very  neutral,   being   made   as    settled   soaps,   but 
given  an  extra  wash  change  after  strengthening  strongly. 
They  are  then  finished  as  usual  and  run  into  barrels.     If 
framed    too    hot,    the    high    percentage    of    cocoanut    oil 
causes  mottling,  which  is  prevented  by  crutching  by  hand 
until  the  temperature  of  the  soap  is  140°-145°   F.     Some 
typical  charges,  all  of  which  are  saponified  with  soda  lye, 
follow  : 

I. 
Palm  Kernel  Oil  ......................     60  parts 

Corn  Oil   .............................     40 

II. 

Palm  Kernel  Oil  .......................     30       " 

Red  Oil  (single  pressed)  ..............     70 

III 

Red  Oil  ..............................    3V/3   " 

Corn  Oil   .............................     33^    " 

Cocoanut  Oil  or  Palm  Kernel  Oil  ...... 


SOAPS   USED  IN   THE  SILK   INDUSTRY. 

Soap  is  used  to  a  very  large  extent  in  silk  mills,  both  for 
101 


:   SOAP-MAKING    MANUAL 

degumming  the  raw  silk  and  in  silk  dyeing.  Raw  silk  con- 
sists of  the  true  silk  fibre  known  as  fibroin  and  a  gummy 
coating,  sericin,  which  dulls  the  lustre  of  the  silk  unless 
removed.  For  this  purpose  a  slightly  alkaline  olive  oil 
foots  soap  is  best  adapted,  although  palm  oil  and  peanut 
oil  soaps  are  sometimes  used,  as  well  as  soaps  made  from 
a  combination  of  house  grease  to  the  extent  of  30  per 
cent.,  together  with  red  oil  or  straight  olein  soaps,  both 
of  which  are  artificially  colored  green.  In  using  house 
grease,  if  30  per  cent,  is  exceeded  in  combination  with 
red  oil,  the  titer  is  raised  to  such  an  extent  that  the 
soap  does  not  readily  rinse  from  the  silk  nor  dissolve 
readily.  They  are  also  not  advisable  because  they  impart 
a  disagreeable  odor  to  the  silk. 

To  make  a  soap  for  this  purpose  from  olive  oil  foots  it 
is  made  as  a  settled  soap,  care  being  taken  to  thoroughly 
boil  the  mass  on  the  saponification  change  in  the  closed 
state  to  assure  proper  saponification.  The  kettle  is  usually 
grained  with  lye  and  given  a  good  wash  change  to  remove 
the  excess  strength.  The  change  previous  to  the  finish 
should  not  be  too  heavy  or  too  large  a  nigre  results.  The 
lighter  the  grain  is,  the  better  the  finished  kettle  is.  A 
yield  of  ISO  per  cent,  is  usually  obtained.  This  soap  is 
generally  run  to  a  frame,  slabbed  upon  cooling  and  packed 
directly  into  wooden  cases. 

For  silk  dyeing  the  above  soap  is  suitable,  although  any 
well-made  soap  of  good  odor  and  not  rancid  is  useable. 
While  soap  alone  is  often  used  in  the  bath  for  silk  dyeing, 
certain  dyestuffs  require  the  addition  of  acetic  or  sulphuric 
acid,  which  sets  free  the  fatty  acids.  If  these  be  of  bad 
odor  it  is  taken  up  by  the  silk  and  is  difficult  to  remove. 
The  most  generally  used  soaps  are  the  just  mentioned  olive 
foots  soap  or  a  soap  made  from  a  good  grade  red  oil. 

Both  kinds  are  extensively  used. 

102 


CLASSIFICATION     OF    SOAPS 

SOAPS  USED  FOR  COTTON  GOODS. 

In  the  manufacture  of  cotton  goods,  as  compared  to  the 
wool  and  silk  industries,  very  much  less  soap  is  used  and 
it  is  only  applied  to  the  finished  fabric  either  to  clean  the 
cloth  preparatory  to  dyeing  or  to  aid  in  dyeing  with  certain 
colors.  It  is  also  used  in  calico  printing.  For  cleansing 
the  cloth  ordinary  chip  soap  is  suitable  although  a  more 
alkaline  soap  finished  as  a  curd  soap  is  an  advantage  in 
that  the  free  alkali  contained  therein  aids  in  removing  the 
dirt  and  has  no  harmful  effect  on  the  cotton.  For  dyeing 
cotton  goods  or  to  brighten  certain  colors  after  dyeing 
an  olive  oil  foots  soap  is  most  generally  employed.  In 
calico  printing  soap  is  used  to  wash  and  clear  the  cloth 
after  printing.  A  soap  for  this  purpose  should  be  easily 
soluble  in  water  and  contain  no  free  alkali,  rosin  or  filler. 
The  best  soaps  for  use  in  calico  printing  are  either  an  olive 
oil  foots  soap  or  an  olein  soap. 

SULPHONATED    OILS. 

While  sulphonated  oils  are  not  usej  to  any  great  extent 
in  the  manufacture  of  soap,  they  are  used  very  largely  in 
the  dyeing  and  printing  of  turkey  and  alizarine  reds  on 
cotton  as  well  as  other  colors.  Just  what  action  these  oils 
have  is  not  known.  Turkey  red  oil  or  sulphonated  castor 
oil  is  the  best  known  sulphonated  oil. 

The  process  of  making  these  oils  is  simple.  The  equip- 
ment necessary  is  a  wooden  tank  or  barrel  of  suitable 
capacity,  approximately  two  and  a  half  times  the  amount 
of  oil  to  be  treated.  There  are  furthermore  required 
other  tanks  or  vessels  to  hold  the  solutions  used  such  as 
caustic  soda,  ammonia  and  acid.  The  tank  to  be  used  for 
the  preparation  of  sulphonated  oil  should  be  provided 
with  a  valve  at  the  bottom  of  the  tank  and  a  gauge  to 
measure  the  quantity  of  liquid  therein. 

103 


SOAP-MAKING    MANUAL 

The  process  is  carried  out  as  follows : 

Three  hundred  pounds  of  castor  oil  are  placed  in  the 
tank  and  80  pounds  at  66  deg.  B.  sulphuric  acid  are 
weighed  out  in  another  vessel.  The  acid  is  run  into 
the  tank  containing  the  oil  in  a  very  thin  stream  while 
the  oil  is  well  stirred.  At  no  time  should  the  temperature 
exceed  40  deg.  C.  This  operation  should  consume  at 
least  an  hour  and  stirring  should  be  continued  half  an 
hour  longer  to  insure  the  thorough  mixing  of  the  oil  with 
the  acid.  The  mass  is  then  allowed  to  settle  for  24 
hours,  after  which  40  gallons  of  water  are  added  and  the 
mixture  stirred  until  it  has  a  uniform  creamy  color  indi- 
cating no  dark  streaks.  This  mixing  process  should  be 
carefully  carried  out  and  when  completed  allowed  to  settle 
36  hours.  At  this  point  the  mass  will  have  separated  into 
two  layers,  the  lower  layer  consisting  of  a  water  solution 
of  acid  and  the  upper  layer  of  oil.  The  former  is  run  out 
through  the  valve  located  at  the  bottom  of  the  tank.  An- 
other wash  may  now  be  given  or  dispensed  with  as  de- 
sired. In  this  wash  the  addition  of  salt  or  sodium  sulphate 
at  the  rate  of  \l/2  pounds  per  gallon  of  water  is  advisable. 
A  24  deg.  B.  caustic  soda  solution  is  prepared  and  added 
slowly  to  the  acidified  oil  with  constant  stirring.  The 
mass  first  turns  creamy,  then  becomes  streaked,  increasing 
in  streaks  as  the  caustic  solution  is  poured  in,  and  finally 
becomes  clear  and  transparent.  Water  is  now  added 
to  bring  the  volume  to  75  gallons.  The  oil  is  now  milky 
in  appearance,  but  the  addition  of  a  little  more  soda  solu- 
tion restores  the  transparency. 

In  some  cases  ammonia  is  used  in  addition  to  caustic 
soda  in  neutralizing  the  oil.  Three-fourths  of  the  amount 
of  caustic  soda  required  to  complete  the  neutralization  is 
first  added  and  then  the  neutralization  is  completed  with 
a  one  to  one  liquid  ammonia  and  water  solution. 

104 


CHAPTER   V 

Glycerine    Recovery. 

The  recovery  of  glycerine  is  very  closely  allied  with  the 
soap-making  industry,  because  glycerine  is  the  very  valuable 
by-product  obtained  in  the  saponification  of  oils  and  fats. 
No  soap  plant  is,  therefore,  fully  equipped  unless  it  has 
some  method  whereby  the  glycerine  is  recovered  and  the 
importance  of  recovering  this  product  cannot  be  too  strong- 
ly emphasized. 

It  has  already  been  pointed  out  that  neutral  fats  or  the 
glycerides  are  a  combination  of  fatty  acid  with  glycerine. 
These  are  split  apart  in  the  process  of  saponification.  While 
by  the  term  saponification  as  used  in  soap  making  it  is  in- 
ferred that  this  is  the  combination  of  caustic  alkalis  with 
the  fatty  acids  to  form  soap,  this  term  is  by  no  means  lim- 
ited to  this  method  of  saponification,  as  there  are  various 
other  methods  of  saponifying  a  fat.  The  chemical  defini- 
tion of  saponification  is  the  conversion  of  an  ester,  of  which 
glycerides  are  merely  a  certain  type,  into  an  alcohol  and 
an  acid  or  a  salt  of  this  acid.  Thus,  if  we  use  caustic 
alkali  as  our  saponifying  agent  for  a  fat  or  oil,  we  obtain 
the  sodium  or  potassium  salt  of  the  higher  fatty  acids  or 
soap  and  the  alcohol,  glycerine.  On  the  other  hand,  if  we 
use  a  mineral  acid  as  the  saponifying  agent,  we  obtain  the 
fatty  acids  themselves  in  addition  to  glycerine.  While  the 
former  is  by  far  the  most  generally  employed  for  making 
soap,  other  processes  consist  in  saponifying  the  fats  by 
some  method  other  than  caustic  alkalis  and  then  convert- 
ing the  fatty  acids  into  soap  by  either  neutralizing  them 
with  sodium  or  potassium  carbonate  or  hydrate. 

It  is  important  to  again  point  out  here  that  fats  and  oils 
105 


SOAP-MAKING    MANUAL 

develop  free  fatty  acid  of  themselves  and  that  the  devel- 
opment of  this  acid  represents  a  loss  in  glycerine.  The 
selection  of  an  oil  or  fat  for  soap  making  should  therefore 
to  a  large  extent  be  judged  as  to  its  adaptability  by  the  free 
fatty  acid  content,  as  the  higher  this  content  is,  the  greater 
is  the  loss  in  the  glycerine  eventually  obtained.  Glycerine 
often  represents  the  only  profit  to  a  soap  manufacturer. 
It  is  indeed  necessary  to  determine  the  percentage  of 
free  fatty  acid  before  purchasing  a  lot  of  stock  to  be  made 
into  soap. 

In  taking  up  the  question  of  glycerine  recovery  we  will 
consider  the  various  methods  thus: 

1.  Where  the  glycerine  is  obtained  from  spent  lye  by 
saponifying  the  fats  or  oils  with  caustic  alkali. 

2.  Where  the  glycerine  is  obtained  by  saponifying  the 
fats  or  oils  by  some  other  method  than  the  above,  of  which 
there  are  the  following: 

(a)  Twitchell  process. 

(b)  Saponification  by  lime  in  autoclave. 

(c)  Saponification  by  acid. 

(d)  Saponification  by  water  in  autoclave. 

(e)  Fermentative    (Enzyms) 

(f)  Krebitz  process. 

RECOVERY    OF    GLYCERINE   FROM    SPENT    LYE. 

The  spent  lye  obtained  from  the  glycerine  changes  in 
making  soap  varies  greatly,  the  quality  depending  upon  the 
stock  saponified  and  the  soap  maker's  care  in  handling  the 
operation.  No  two  lyes  run  exactly  alike  as  to  proportion 
of  the  various  ingredients,  although  they  are  all  similar 
in  containing  the  same  substances  either  in  solution  or 
suspension.  Spent  lye  is  a  water  solution  of  mainly  glyc- 
erine, free  alkali  either  as  caustic  alkali  or  carbonate  and 
salt,  including  sodium  sulfate,  but  furthermore  contains 
some  soap  and  albuminous  matter  either  in  solution  or 

106 


GLYCERINE    RECOVERY 

suspension.  Upon  standing  in  the  storage  tank  the  greater 
part  of  the  soap  usually  separates  when  the  lye  cools.  In 
order  to  assure  the  greatest  economical  yield  of  glycerine 
by  saponifying  a  fat  with  caustic  soda  it  is  necessary  to 
obtain  a  proportion  of  three  parts  of  water  to  every  part 
of  fat  made  into  soap.  Test  runs  have  shown  that  this  is 
the  proper  proportion  and  that  it  is  not  economical  to 
greatly  exceed  this  amount,  and  if  a  much  less  proportion 
is  used  the  full  yield  of  glycerine  is  not  obtained. 

The  spent  lyes  contain  varying  amounts  of  glycerine, 
the  first  change  being  richest  in  glycerine  content,  and  this 
being  reduced  in  the  subsequent  changes.  If  the  lyes  al- 
ways run  high  in  glycerine  it  is  an  indication  that  it  is  not 
all  being  obtained.  The  usual  percentage  is  from  0.5%  to 
5%  or  even  more,  although  the  average  is  somewhere 
around  2%  to  3%.  The  lye  as  it  comes  from  the  kettle 
should  not  contain  any  more  than  0.5%  to  0.6%  of  free 
alkali  calculated  as  sodium  carbonate,  Na2COs.  If  the  pro- 
portion is  higher  than  this,  it  shows  that  the  saponification 
has  been  conducted  with  too  high  a  proportion  of  alkali, 
a  condition  which  should  be  corrected  in  the  kettle  room. 
An  excess  of  free  alkali  does  not  interfere  to  any  great 
extent  with  the  successful  recovery  of  the  glycerine,  but 
is  a  waste  of  both  alkali  and  the  acid  used  in  neutralizing 
this.  It  is,  therefore,  more  economical  to  run  a  strong  lye 
over  fresh  stock  and  neutralize  the  alkali  thus,  rather  than 
treating  the  lye  for  glycerine  recovery. 

Before  the  spent  lye  can  be  run  into  the  evaporator  it  is 
necessary  to  remove  the  albuminous  impurities  and  soap 
and  to  neutralize  the  excess  alkali  to  between  exactly  neu- 
tral and  0.02%  alkalinity.  The  lye  should  never  be  fed 
into  the  evaporator  in  the  acid  condition. 

In  order  to  treat  the  spent  lyes  for  evaporation,  they  are 
first  allowed  to  cool  in  the  storage  tank,  after  which  any 

107 


SOAP-MAKING     MANUAL 

soap  which  may  have  separated  is  skimmed  off  and  re- 
turned to  the  soap  kettle.  This  lye  is  then  pumped  to  the 
treatment  tank,  an  ordinary  tank  equipped  with  some 
method  of  agitating  the  liquor,  either  by  a  mechanical 
stirrer,  steam  blower  or  compressed  air,  until  it  is  about 
two  feet  from  the  top. 

After  the  lye  has  been  skimmed  off  it  is  thoroughly 
agitated  and  a  sample  taken.  The  amount  of  lye  in  the 
tank  is  then  calculated.  Spent  lye  is  about  1.09  times 
heavier  than  water,  or  weighs  about  9  pounds  to  the  gallon. 
While  the  sample  is  being  tested  for  alkalinity  it  is  advis- 
able to  add  sulfate  of  alumina,  which  may  be  dissolving 
while  the  sample  is  being  titrated.  This  substance  should 
be  added  in  the  proportion  of  anywhere  from  6  to  14 
pounds  per  thousand  pounds  of  lye,  depending  upon  the 
amount  of  impurities  contained  therein.  For  a  clean  lye 
six  pounds  per  thousand  is  sufficient,  but  for  an  impure 
lye  a  greater  quantity  is  necessary.  The  sulfate  of 
alumina  used  should  be  free  from  arsenic  and  sulfides  and 
should  contain  a  minimum  amount  of  grit  (silica),  as  grit 
reduces  the  life  of  the  pump  valves.  This  may  be  esti- 
mated with  sufficient  accuracy  by  rubbing  the  filtered-off 
portions,  insoluble  in  water  between  the  fingers  and  a 
plate  of  glass.  The  object  of  adding  the  sulfate  of  alumina 
is  to  transform  the  soap  contained  in  the  lye  into  the  in- 
soluble aluminum  soaps,  and  at  the  same  time  to  coagulate 
the  albuminous  impurities.  It  must  be  remembered  that 
the  sulfate  of  alumina  is  added  only  for  the  fresh  lye  put 
into  the  tank.  Thus  if  there  were  10,000  pounds  of  lye  in 
the  treating  tank  when  the  fresh  lye  was  run  in,  and  50,000 
pounds  when  the  tank  is  filled,  adding  nine  pounds  of 
sulfate  of  alumina  per  thousand  of  lye,  only  360  pounds 
would  be  added  or  enough  for  40,000  pounds.  Sulfate  of 
alumina  neutralizes  one-third  of  its  weight  of  caustic. 

108 


GLYCERINE    RECOVERY 

To  determine  the  alkali  in  the  sample,  10  cubic  centime- 
ters are  pipetted  into  a  beaker,  a  little  distilled  water  added, 
then  3  or  4  drops  of  phenolphthalein  indicator.  From  a 
burette,  quarter  normal  (N/4)  sulfuric  acid  is  added  until 
the  pink  color  is  just  discharged.  When  this  point  is 
reached  4  to  5  c.  c.  more  of  acid  are  added  and  the  solution 
is  boiled  to  expel  the  carbon  dioxide.  Should  the  solution 
turn  pink,  it  is  necessary  to  add  more  acid.  After  having 
boiled  for  3  to  4  minutes,  N/4  caustic  soda  is  added  until 
the  pink  color  just  returns  and  the  amount  of  caustic  soda 
used  is  read  on  the  burette.  The  difference  between  the 
number  of  cubic  centimeters  of  N/4  sulfuric  acid  and  N/4 
caustic  soda  gives  the  amount  of  alkali  in  the  sample.  By 
using  a  10  c.  c.  sample  and  N/4  sulfuric  acid  and  N/4 
caustic  soda  each  c.  c.  obtained  by  the  difference  of  these 
two  solutions  is  equal  to  one-tenth  of  one  per  cent.  (0.1%) 
of  the  total  alkali  in  the  lye.  As  an  example,  say  we  first  used 
7.7  c.  c.  of  N/4  sulfuric  acid  to  just  discharge  the  pink,  then 
added  4  c.  c.  more,  or  11.7  c.  c.  in  total.  After  boiling  it  re- 
quired 5.3  c.  c.  to  bring  back  a  slight  pink,  the  total. alkalin- 
ity would  be  11.7  c.  c.  —  5.3  c.  c.  =  6.4  c.  c.,  or  0.64%  total 
alkali  in  the  lye  in  terms  of  caustic  soda.  If  there  were 
40,000  pounds  of  lye  to  be  treated  then  we  should  have  to 
neutralize : 

40,000  X  .0064  =  256  Ibs.  alkali.  Since  sulfate  of  alumina 
neutralizes  one-third  of  its  weight  in  caustic,  and  there  are 
say  9  Ibs.  of  this  added  per  thousand  pounds  of  lye  we 
would  add 

40,000  X  9  =  360  Ibs.  of  sulfate  of  alumina.  This  would 
neutralize 

360  X  */3  =  120  Ibs  of  alkali.  There  are  then  256  —  120 
=  136  Ibs.  of  alkali  still  to  be  neutralized.  If  60°  B.  sul- 
furic acid  is  used  it  requires  about  1.54  Ibs.  of  acid  to  one 
pound  of  caustic.  Therefore  to  neutralize  the  caustic 
soda  remaining  it  requires : 

109 


SOAP-MAKING     MANUAL 

136  X  1-54  =  209.44  Ibs.  60°  B.  stilfuric  acid  to  neutral- 
ize the  total  alkali  in  the  40,000  pounds  of  spent  lye. 

The  acid  is  added  and  the  lye  well  stirred,  after  which 
another  sample  is  taken  and  again  titrated  as  before.  From 
this  titration  the  amount  of  acid  to  be  added  is  again  cal- 
culated and  more  acid  is  added  if  necessary.  Should  too 
much  acid  have  been  added,  caustic  soda  solution  is  added 
until  the  lye  is  between  exactly  neutral  and  0.02%  alkaline. 
The  filtered  lyes  at  this  stage  have  a  slight  yellowish  cast. 

To  be  sure  that  the  lyes  are  treated  correctly  the  precipi- 
tation test  is  advisable.  To  carry  this  out  filter  about  50 
c.  c.  of  the  treated  lye  and  divide  into  two  portions  in  a 
test  tube.  To  one  portion  add  ammonia  drop  by  drop.  If 
a  cloudiness  develops  upon  shaking,  more  alkali  is  added 
to  the  lye  in  the  tank.  To  the  other  portion  add  a  few 
drops  of  1  to  5  sulfuric  acid  and  shake  the  test  tube.  If 
a  precipitate  develops  or  the  solution  clouds,  more  acid  is 
needed.  When  the  lyes  are  treated  right  no  cloudiness 
should  develop  either  upon  adding  ammonia  or  the  di- 
lute acid. 

The  properly  treated  lye  is  then  run  through  the  filter 
press  while  slightly  warm  and  the  filtered  lye  is  fed  to  the 
evaporator  from  the  filtered  lye  tank.  The  lye  coming 
from  the  filter  press  should  be  clear  and  have  a  slight 
yellowish  cast.  As  the  pressure  increases  it  is  necessary  to 
clean  the  press  or  some  of  the  press  cake  will  pass  through 
the  cloths.  Where  sodium  silicate  is  used  as  a  filler,  the 
silicate  scrap  should  never  be  returned  to  the  soap  kettle 
until  the  glycerine  lyes  have  been  withdrawn.  This  practice 
of  some  soapmakers  is  to  be  strongly  censured,  as  it 
causes  decided  difficulty  in  filtering  the  lye,  since  during 
the  treatment  of  the  lye,  free  silicic  acid  in  colloidal  form  is 
produced  by  the  decomposition  of  the  sodium  silicate  by 
acid.  This  often  prevents  filtering  the  treated  lye  even  at 

110 


GLYCERINE    RECOVERY 

excess   pressure  and    at    its    best    retards     the    filtering. 

As  to  the  filter  press  cake,  this  may  be  best  thrown  away 
in  a  small  factory.  Where,  however,  the  output  of  glycerine 
is  very  large  it  pays  to  recover  both  the  fatty  acids  and 
alumina  in  the  press  cakes. 

In  some  cases,  especially  when  the  lyes  are  very  dirty 
and  the  total  residue  in  the  crude  glycerine  runs  high,  for 
which  there  is  a  penalty  usually  attached,  a  double  filtra- 
tration  of  the  lye  is  advisable.  This  is  carried  out  by  first 
making  the  lye  slightly  acid  in  reaction  by  the  addition 
of  alum  and  acid,  then  filtering.  This  filtered  lye  is  then 
neutralized  to  the  proper  point  with  caustic,  as  already 
described,  and  passed  through  the  filter  press  again. 

While  in  the  method  of  treating  the  lyes  as  given  sul- 
furic  acid  is  used  for  neutralizing,  some  operators  prefer 
to  use  hydrochloric  acid,  as  this  forms  sodium  chloride  or 
common  salt,  whereas  sulfuric  acid  forms  sodium  sul- 
fate,  having  2/5  the  graining  power  of  salt,  which  event- 
ually renders  the  salt  useless  for  graining  the  soap,  as  the 
percentage  of  sodium  sulfate  increases  in  the  salt.  When 
the  salt  contains  25  per  cent,  sodium  sulfate  it  is  advisable 
to  throw  it  away.  Sulfuric  acid,  however,  is  considerably 
cheaper  than  hydrochloric  and  this  more  than  compensates 
the  necessity  of  having  to  eventually  reject  the  recovered 
salt.  It  may  here  also  be  mentioned  that  recovered  salt 
contains  5-7  per  cent,  glycerine  which  should  be  washed 
out  in  the  evaporator  before  it  is  thrown  away.  The  follow- 
ing tables  give  the  approximate  theoretical  amounts  of 
acids  of  various  strengths  required  to  neutralize  one 
pound  of  caustic  soda : 

For  1  pound  of  caustic  soda — 

3.25  Ibs.  18°  B.  hydrochloric  (muriatic)   acid  are  required. 
2.92    "     20°  B.  "  "  "      " 

2.58    "     22°  B.  "  "  "      " 

ill 


SOAP-MAKING     MANUAL 

For  1  pound  of  caustic  soda — 

1.93  Ibs.  50°  B.  sulphuric  acid  are  required. 
1.54    "    60°  B.  "  "     " 

1.28    "    66°  B.          "          "     " 

It  is,  of  course,  feasible  to  neutralize  the  spent  lye  with- 
out first  determining  the  causticity  by  titrating  a  sample  and 
this  is  often  the  case.  The  operator  under  such  conditions 
first  adds  the  sulfate  of  alumina,  then  the  acid,  using 
litmus  paper  as  his  indicator.  Comparatively,  this  method 
of  treatment  is  much  slower  and  not  as  positive,  as  the 
amount  of  acid  or  alkali  to  be  added  is  at  all  times  un- 
certain, for  in  the  foaming  of  the  lyes  their  action  on  litmus 
is  misleading! 

After  the  lye  has  been  filtered  to  the  filtered  lye  tank  h 
is  fed  to  the  evaporator,  the  method  of  operation  of  which 
varies  somewhat  with  different  styles  or  makes.  When  it 
first  enters  trie  evaporator  the  lye  is  about  11°-12°  B.  After 
boiling  the  density  will  gradually  rise  to  27°  B.  and  remain 
at  this  gravity  for  some  time  and  during  which  time  most 
of  the  salt  is  dropped  out  in  the  salt  filter.  As  the  lye 
concentrates  the  gravity  gradually  rises  to  28°-30°  B.,  which 
is  half  crude  glycerine  and  contains  about  60  per  cent, 
glycerine.  Some  operators  carry  the  evaporation  to  this 
point  and  accumulate  a  quantity  of  half  crude  before  going 
on  to  crude.  After  half  crude  is  obtained  the  temperature 
on  the  evaporator  increases,  the  vacuum  increases  and  the 
pressure  on  the  condensation  drain  goes  up  (using  the  same 
amount  of  live  steam).  As  the  liquor  grows  heavier  the 
amount  of  evaporation  is  less,  and  less  steam  is  required 
necessitating  the  regulation  of  the  steam  pressure  on  the 
drum.  When  a  temperature  of  210°  F.  on  the  evaporator, 
with  26  or  more  inches  vacuum  on  the  pump  is  arrived  at, 
the  crude  stage  has  been  reached  and  the  liquor  now  con- 
tains about  80  per  cent,  glycerine  in  which  shape  it  is 

112 


GLYCERINE    RECOVERY 

usually  sold  by  soap  manufacturers.  A  greater  concen- 
tration requires  more  intricate  apparatus.  After  settling  a 
day  in  the  crude  tank  it  is  drummed. 

Crude  glycerine  (about  80  per  cent,  glycerol)  free  from 
salt  is  33°  B.,  or  has  a  specific  gravity  of  1.3.  A  sample 
boiled  in  an  open  dish  boils  at  a  temperature  of  155°  C. 
or  over. 

TWITCHELL  PROCESS. 

The  Twitchell  process  of  saponification  consists  of  caus- 
ing an  almost  complete  cleavage  of  fats  and  oils  by  the  use 
of  the  Twitchell  reagent  or  saponifier,  a  sulfo-aromatic 
compound.  This  is  made  by  the  action  of  concentrated 
sulfuric  acid  upon  a  solution  of  oleic  acid  or  stearic  acid 
in  an  aromatic  hydrocarbon.  From  0.5  per  cent,  to  3  per 
cent,  of  the  reagent  is  added  and  saponification  takes  place 
from  12-48  hours  by  heating  in  a  current  of  live  steam 
The  reaction  is  usually  accelerated  by  the  presence  of  a  few 
per  cent,  of  free  fatty  acids  as  a  starter.  Recently  the 
Twitchell  double  reagent  has  been  introduced  through 
which  it  is  claimed  that  better  colored  fatty  acids  are  ob- 
tained and  the  glycerine  is  free  from  ash. 

The  advantages  claimed  for  the  Twitchell  process  as 
outlined  by  Joslin1  are  as  follows : 

1.  All  the  glycerine  is  separated  from  the  stock  before 
entering  the  kettle,  preventing  loss  of  glycerine  in  the  soap 
and  removing  glycerine  from  spent  lye. 

2.  The  liquors  contain  15-20  per  cent,  glycerine  whereas 
spent    lyes    contain    but    3-5    per    cent,    necessitating    less 
evaporation   and  consequently  being   more   economical    in 
steam,  labor  and  time. 

3.  No  salt  is  obtained  in  the  liquors  which  makes  the 
evaporation  cheaper  and  removes  the  cause  of  corrosion  of 


^ourn.  Ind.   Eng.  Chem.   (1909),  I,  p.  654. 
113 


SOAP-MAKING     MANUAL 

the  evaporator;  also  saves  the  glycerine  retained  by  the 
salt. 

4.  The  glycerine  liquors  are  purer  and  thus  the  treatment 
of  the  lyes  is  cheaper  and  simpler  and  the  evaporation 
less  difficult. 

5.  The  glycerine  can  readily  be  evaporated  to  90  per  cent, 
crude  rather  than  80  per  cent,  crude,  thus  saving  drums, 
labor  in  handling  and  freight.    The  glycerine  furthermore 
receives  a  higher  rating  and  price,  being  known  as  saponi- 
fication  crude  which  develops  no  glycols  in  refining  it. 

6.  The  fatty  acids  obtained  by  the  Twitchell  saponifier 
may  be  converted   into   soap   by   carbonates,   thus   saving 
cost  in  alkali. 

7.  There    is    a    decrease    in    the    odor    of    many    strong 
smelling  stocks. 

8.  The  glycerine  may  be  obtained  from  half  boiled  and 
cold  made  soaps  as  well  as  soft  (potash)  soaps. 

While  the  advantages  thus  outlined  are  of  decided  value 
in  the  employment  of  the  Twitchell  process,  the  one  great 
disadvantage  is  that  the  fatty  acids  obtained  are  rather 
dark  in  color  and  are  not  satisfactorily  employed  for  the 
making  of  a  soap  where  whiteness  of  color  is  desired. 

To  carry  out  the  process  the  previously  heated  oil  or 
fat  to  be  saponified  is  run  into  a  lead  lined  tank.  As 
greases  and  tallow  often  contain  impurities  a  preliminary 
treatment  with  sulfuric  acid  is  necessary.  For  a  grease 
1.25  per  cent,  of  half  water  and  half  66°  B.  sulfuric  acid 
is  the  approximate  amount.  The  undiluted  66°  B.  acid 
should  never  be  added  directly,  as  the  grease  would  be 
charred  by  this.  The  grease  should  be  agitated  by  steam 
after  the  required  percentage  of  acid,  calculated  on  the 
weight  of  the  grease,  has  been  added.  The  wash  lye 
coming  off  should  be  7°-10°  B.  on  a  good  clean  grease  or 
15°-22*  B.  on  cotton  oil  or  a  poor  grease.  As  has  been 

114 


GLYCERINE    RECOVERY 

stated  the  grease  is  heated  before  the  acid  is  added  or  the 
condensation  of  the  steam  necessitates  the  addition  of  more 
acid.  After  having  boiled  for  1-2  hours  the  grease  is 
allowed  to  settle  for  12  hours  and  run  off  through  a  swivel 
pipe. 

After  the  grease  has  been  washed,  as  just  explained, 
and  settled,  it  is  pumped  into  a  covered  wooden  tank  con- 
taining an  open  brass  coil.  Some  of  the  second  lye  from 
a  previous  run  is  usually  left  in  this  tank  and  the  grease 
pumped  into  this.  The  amount  of  this  lye  should  be  about 
one-third  to  one-half  the  weight  of  the  grease  so  that  there 
is  about  60  per  cent,  by  weight  of  grease  in  the  tank  after 
24  hours  boiling.  Where  occasions  arise  when  there  is  no 
second  lye  about  50  per  cent,  by  weight  of  distilled  water 
to  the  amount  of  grease  is  run  into  the  tank  to  replace  the 
lye.  The  saponifier  is  then  added  through  a  glass  or 
granite  ware  funnel  after  the  contents  of  the  tank  have 
been  brought  to  a  boil.  If  the  boiling  is  to  be  continued 
48  hours,  1  per  cent,  of  saponifier  is  added.  For  24  hours 
boiling  add  1.5  per  cent.  The  boiling  is  continued  for  24-48 
hours  allowing  18  inches  for  boiling  room  or  the  grease 
will  boil  over. 

After  boiling  has  continued  the  required  length  of  time 
the  mass  is  settled  and  the  glycerine  water  is  drawn  off  to 
the  treatment  tank.  Should  a  permanent  emulsion  have 
formed,  due  to  adding  too  great  an  amount  of  saponifier, 
a  little  sulfuric  acid  (0.1  per  cent-0.3  per  cent.)  will 
readily  break  this.  During  the  time  this  is  being  done  the 
space  between  the  grease  and  the  cover  on  the  tank  is  kept 
filled  with  steam  as  contact  with  the  air  darkens  the  fatty 
acids. 

To  the  grease  remaining  in  the  tank  distilled  water  (con- 
densed water  from  steam  coils)  to  one-half  its  volume  is 
added  and  the  boiling  continued  12-24  hours.  The  grease 

US 


SOAP-MAKING     MANUAL 

is  then  settled  and  the  clear  grease  run  off  through  a 
swivel  pipe.  A  layer  of  emulsion  usually  forms  between 
the  clear  grease  and  lye  so  that  it  may  easily  be  de- 
termined when  the  grease  has  all  been  run  off.  To  pre- 
vent discoloration  of  the  fatty  acids  it  is  necessary  to 
neutralize  the  lye  with  barium  carbonate.  The  amount  of 
this  to  be  added  depends  upon  the  percentage  of  saponifier 
used.  About  1/10  the  weight  of  saponifier  is  the  right 
amount.  The  barium  carbonate  is  added  through  the  fun- 
nel at  the  top  of  the  tank  mixed  with  a  little  water  and 
the  lye  tested  until  it  is  neutral  to  methyl  orange  indicator. 
When  the  fatty  acids  are  thus  treated  they  will  not  darken 
upon  exposure  to  the  air  when  run  off. 

Fresh  grease  is  now  pumped  into  the  lye  or  water  re- 
maining in  the  tank  and  the  process  repeated. 

The  glycerine  water  or  first  lye  is  run  to  the  treatment 
tank,  the  fat  skimmed  off  and  neutralized  with  lime  until  it 
shows  pink  with  phenolphthalein,  after  having  been  thor- 
oughly boiled  with  steam.  About  0.25  per  cent,  lime  is  the 
proper  amount  to  add.  The  mixture  is  then  allowed  to 
settle  and  the  supernatant  mixture  drawn  off  and  run  to  the 
glycerine  evaporator  feed  tank.  The  lime  which  holds 
considerable  glycerine  is  filtered  and  the  liquor  added  to  the 
other.  The  evaporation  is  carried  out  in  two  stages.  The 
glycerine  water  is  first  evaporated  to  about  60  per  cent, 
glycerol,  then  dropped  into  a  settling  tank  to  settle  out  the 
calcium  sulfate.  The  clear  liquor  is  then  evaporated  to 
crude  (about  90  per  cent,  glycerine)  and  the  sediment 
filtered  and  also  evaporated  to  crude. 

As  to  the  amount  of  saponifier  to  use  on  various  stocks, 
this  is  best  determined  by  experiment  as  to  how  high  a 
percentage  gives  dark  colored  fatty  acids.  For  good  stock 
such  as  clean  tallow,  prime  cottonseed  oil,  corn  oil, 
cocoanut  oil  and  stock  of  this  kind  0.75  per  cent,  saponifier 

116 


GLYCERINE    RECOVERY 

is  sufficient.  For  poorer  grades  of  tallow,  house  grease, 
poor  cottonseed  oil,  etc.,  1  per  cent,  saponifier  is  required 
and  for  poorer  grade  greases  higher  percentages.  The 
percentage  of  fatty  acids  developed  varies  in  various  stocks, 
and  also  varies  with  the  care  that  the  operation  is  carried 
out,  but  is  usually  between  85  per  cent.-95  per  cent.  Due 
to  the  water  taken  up  in  the  saponification  process  there 
is  a  yield  of  about  103  pounds  of  fatty  acids  and  glycerine 
for  100  pounds  of  fat. 

The  Twitchell  reagent  has  undoubtedly  caused  a  decided 
advance  in  the  saponification  of  fats  and  oils  and  has  been 
of  great  value  to  the  soap  manufacturer,  because  wi+h  a 
small  expenditure  it  is  possible  to  compete  with  the  much 
more  expensive  equipment  necessary  for  autoclave  sapon- 
ification. The  drawback,  however,  has  been  that  the 
reagent  imparted  a  dark  color  to  the  fatty  acids  obtained, 
due  to  decomposition  products  forming  when  the  reagent 
is  made,  and  hence  is  not  suitable  for  use  in  soaps  where 
whiteness  of  color  is  desired. 

There  have  recently  been  two  new  reagents  introduced 
which  act  as  catalyzers  in  splitting  fats,  just  as  the  Twitchell 
reagent  acts,  but  the  fatty  acids  produced  by  the  cleavage 
are  of  good  color.  The  saponification,  furthermore,  takes 
place  more  rapidly.  These  are  the  Pfeilring  reagent  and 
Kontact  reagent. 

The  Pfeilring  reagent  is  very  similar  to  the  Twitchell 
reagent,  being  made  from  hydrogenated  castor  oil  and 
naphthalene  by  sulfonation  with  concentrated  sulfuric  acid. 
It  is  manufactured  in  Germany  and  is  being  extensively 
used  in  that  country  with  good  success. 

The  Kontact  or  Petroff  reagent,  discovered  by  Petroff  in 
Russia,  is  made  from  sulfonated  mineral  oils.  Until  very 
recently  it  has  only  been  manufactured  in  Europe,  but  now 
that  it  has  been  found  possible  to  obtain  the  proper  min- 

117 


SOAP-MAKING     MANUAL 

eral  constituent  from  American  petroleum,  it  is  being  manu- 
factured in  this  country,  and  it  is  very  probable  that  it  will 
replace  the  Twitchell  reagent  because  of  the  advantages 
derived  by  using  it,  as  compared  to  the  old  Twitchell 
reagent. 

The  method  and  equipment  necessary  for  employing 
either  the  Pfeilring  or  Kontact  reagents  is  exactly  the 
same  as  in  using  the  Twitchell  process. 

AUTOCLAVE    SAPONIFICATION. 

While  the  introduction  of  the  Twitchell  process  to  a 
great  extent  replaced  the  autoclave  method  of  saponifica- 
tion  for  obtaining  fatty  acids  for  soap  making,  the  auto- 
clave method  is  also  used.  This  process  consists  in  heat- 
ing the  previously  purified  fat  or  oil  in  the  presence  of 
lime  and  water,  or  water  only,  for  several  hours,  which 
causes  a  splitting  of  the  glycerides  into  fatty  acids  and 
glycerine.  The  advantage  of  autoclave  saponification  over 
the  Twitchell  process  is  that  a  greater  cleavage  of  the  fats 
and  oils  results  in  less  time  and  at  a  slightly  less  expense. 
The  glycerine  thus  obtained  is  also  purer  and  of  better 
color  than  that  obtained  by  Twitchelling  the  fats. 

An  autoclave  or  digestor  consists  of  a  strongly  construct- 
ed, closed  cylindrical  tank,  usually  made  of  copper,  and  is 
so  built  as  to  resist  internal  pressure.  The  digestor  is 
usually  3  to  5  feet  in  diameter  and  from  18  to  25  feet  high. 
It  may  be  set  up  horizontally  or  vertically  and  is  covered 
with  an  asbestos  jacket  to  retain  the  heat.  Various  inlets 
and  outlets  for  the  fats,  steam,  etc.,  as  well  as  a  pressure 
gauge  and  safety  valve  are  also  a  necessary  part  o'f  the 
equipment. 

LIME   SAPONIFICATION. 

The  saponification  in  an  autoclave  is  usually  carried  out 
by  introducing  the  fats  into  the  autoclave  with  a  percentage 

118 


GLYCERINE   RECOVERY 

of  lime,  magnesia  or  zinc  oxide,  together  with  water.  If 
the  fats  contain  any  great  amount  of  impurities,  it  is  first 
necessary  to  purify  them  either  by  a  treatment  with  weak 
sulfuric  acid,  as  described  under  the  Twitchell  process,  or 
by  boiling  them  up  with  brine  and  settling  out  the  impuri- 
ties from  the  hot  fat. 

To  charge  the  autoclave  a  partial  vacuum  is  created 
therein  by  condensation  of  steam  just  before  running  the 
purified  oil  in  from  an  elevated  tank.  The  required  quan- 
tity of  unslaked  lime,  2  to  4  per  cent,  of  the  weight  of  the 
fat,  is  run  in  with  the  molten  fat,  together  with  30  per 
cent,  to  SO  per  cent,  of  water.  While  8.7  per  cent,  lime  is 
theoretically  required,  practice  has  shown  that  2  per  cent, 
to  4  per  cent,  is  sufficient.  The  digester,  having  been 
charged  and  adjusted,  steam  is  turned  on  and  a  pressure 
of  8  to  10  atmospheres  maintained  thereon  for  a  period  of 
six  to  ten  hours.  Samples  of  the  fat  are  taken  at 
various  intervals  and  the  percentage  of  free  fatty  acids  de- 
termined. When  the  saponification  is  completed  the  con- 
tents of  the  autoclave  are  removed,  usually  by  blowing  out 
the  digester  into  a  wooden  settling  tank,  or  by  first  running 
off  the  glycerine  water  and  then  blowing  out  the  lime,  soap 
and  fatty  acids.  The  mass  discharged  from  the  digestor 
separates  into  two  layers,  the  upper  consisting  of  a  mix- 
ture of  lime  soap  or  "rock"  and  fatty  acids,  and  the  lower 
layer  contains  the  glycerine  or  "sweet"  water.  The  glycer- 
ine water  is  first  run  off  through  a  clearing  tank  or  oil 
separator,  if  this  has  not  been  done  directly  from  the  auto- 
clave, and  the  mass  remaining  washed  once  or  twice  more 
with  water  to  remove  any  glycerine  still  retained  by  the 
lime  soap.  The  calculated  amount  of  sulfuric  acid  to  de- 
compose the  lime  "rock"  is  then  added,  and  the  mass  agi- 
tated until  the  fatty  acids  contained  therein  are  entirely 
set  free.  Another  small  wash  is  then  given  and  the  wash 

119 


SOAP-MAKING     MANUAL 

water  added  to  the  glycerine  water  already  run  off.  The 
glycerine  water  is  neutralized  with  lime,  filtered  and  con- 
centrated as  in  the  Twitchell  process. 

Due  to  the  difficulties  of  working  the  autoclave  saponifi- 
cation  with  lime,  decomposing  the  large  amount  of  lime 
soap  obtained  and  dealing  with  much  gypsum  formed 
thereby  which  collects  as  a  sediment  and  necessitates  clean- 
ing the  tanks,  other  substances  are  used  to  replace  lime. 
Magnesia,  about  2  per  cent,  of  the  weight  of  the  fat,  is  used 
and  gives  better  results  than  lime.  One-half  to  1  per  cent, 
of  zinc  oxide  of  the  weight  of  the  fat  is  even  better 
adapted  and  is  now  being  extensively  employed  for  this 
purpose.  In  using  zinc  oxide  it  is  possible  to  recover  the 
zinc  salts  and  use  them  over  again  in  the  digester,  which 
makes  the  process  as  cheap  to  work  as  with  lime,  with  far 
more  satisfactory  results. 

ACID    SAPONIFICATION. 

While  it  is  possible  to  saponify  fats  and  oils  in  an  auto- 
clave with  the  addition  of  acid  to  the  fat,  unless  a  specially- 
constructed  digestor  is  built,  the  action  of  the  acid  on  the 
metal  from  which  the  autoclave  is  constructed  prohibits 
its  use.  The  acid  saponification  is  therefore  carried  out  by 
another  method. 

The  method  of  procedure  for  acid  saponification,  there- 
fore, is  to  first  purify  the  fats  with  dilute  acid  as  alread> 
described.  The  purified,  hot  or  warm,  dry  fat  is  then  run 
to  a  specially-built  acidifier  or  a  lead-lined  tank  and  from 
4  per  cent,  to  6  per  cent,  of  concentrated  sulfuric  acid 
added  to  the  fat,  depending  upon  its  character,  the  degree 
of  saponification  required,  temperature  and  time  of  sapon- 
ification. A  temperature  of  110  degrees  C.  is  maintained 
and  the  mass  mixed  from  four  to  six  hours.  The  tank  is 
then  allowed  to  settle  out  the  tar  formed  during  the  sapon- 

120 


GLYCERINE   RECOVERY 

ification,  and  the  fatty  acids  run  off  to  another  tank  and 
boiled  up  about  three  times  with  one-third  the  amount  of 
water.  The  water  thus  obtained  contains  the  glycerine, 
and  after  neutralization  is  concentrated. 

AQUEOUS  SAPONIFICATION. 

While  lime  or  a  similar  substance  is  ordinarily  used  to 
aid  in  splitting  fats  in  an  autoclave,  the  old  water  process 
is  still  used.  This  is  a  convenient,  though  slower  and 
more  dangerous  method,  of  producing  the  hydrolysis  of 
the  glyceride,  as  well  as  the  simplest  in  that  fatty  acids 
and  glycerine  in  a  water  solution  are  obtained.  The  method 
consists  in  merely  charging  the  autoclave  with  fats  and 
adding  about  30  per  cent,  to  40  per  cent,  of  their 
weight  of  water,  depending  on  the  amount  of  free 
fatty  acid  and  subjecting  the  charge  to  a  pres- 
sure of  150  to  300  pounds,  until  the  splitting  has 
taken  place.  This  is  a  much  higher  pressure  than  when 
lime  is  used  and  therefore  a  very  strong  autoclave  is  re- 
quired. Since  fatty  acids  and  pure  glycerine  water  are 
obtained  no  subsequent  treatment  of  the  finished  charge  is 
necessary  except  separating  the  glycerine  water  and  giving 
the  fatty  acids  a  wash  with  water  to  remove  all  the 
glycerine  from  them. 

SPLITTING    FATS    WITH    FERMENTS. 

In  discussing  the  causes  of  rancidity  of  oils  and  fats  it 
was  pointed  out  that  the  initial  splitting  of  these  is  due 
to  enzymes,  organized  ferments.  In  the  seeds  of  the 
castor  oil  plant,  especially  in  the  protoplasm  of  the  seed, 
the  enzyme  which  has  the  property  of  causing  hydrolysis 
of  the  glycerides  is  found.  The  ferment  from  the  seeds 
of  the  castor  oil  plant  is  now  extracted  and  used  upon  a 
commercial  basis  for  splitting  fats. 

The  equipment  necessary  to  carry  out  this  method  of 

121 


SOAP-MAKING    MANUAL 

saponification  is  a  round,  iron,  lead-lined  tank  with  a  conical 
bottom,  preferably  about  twice  as  long  as  it  is  wide.  Open 
and  closed  steam  coils  are  also  necessary  in  the  tank. 

The  oils  are  first  heated  and  run  into  this  tank.  The 
right  temperature  to  heat  these  to  is  about  1  degree  to  2 
degrees  above  their  solidification  point.  For  liquid  oils 
23  degrees  C.  is  the  proper  heat  as  under  20  degrees  C. 
the  cleavage  takes  place  slowly.  Fats  titering  44  degrees 
C.  or  above  must  be  brought  down  in  titer  by  mixing 
with  them  oils  of  a  lower  titer  as  the  ferment  or  enzyme 
is  killed  at  about  45  degrees  C.  and  thus  loses  its  power 
of  splitting.  It  is  also  necessary  to  have  the  fat  in  the 
liquid  state  or  the  ferment  does  not  act.  The  proper 
temperature  must  be  maintained  with  dry  steam. 

It  is,  of  course,  necessary  to  add  water,  which  may  be  any 
kind  desired,  condensed,  water  from  steam  coils,  well,  city, 
etc.  From  30  per  cent,  to  40  per  cent.,  on  the  average  35 
per  cent,  of  water  is  added,  as  the  amount  necessary  is 
regulated  so  as  to  not  dilute  the  glycerine  water  unneces- 
sarily. To  increase  the  hydrolysis  a  catalyzer,  some  neu- 
tral salt,  usually  manganese  sulfate  is  added  in  the  propor- 
tion of  0.15  per  cent,  appears  to  vary  directly  as  the 
saponification  number  of  the  fat  or  oil.  The  approximate 
percentages  of  fermentive  substance  to  be  added  to  various 
oils  and  fats  follow : 

Cocoanut  oil   8     % 

Palm  Kernel  oil 8      % 

Cottonseed  oil   6-7  % 

Linseed  oil   4-5  % 

Tallow  oil 8-10% 

The  oil,  water,  manganese  sulfate  and  ferment  having 
been  placed  in  the  tank  in  the  order  named,  the  mixture  is 
agitated  with  air  for  about  a  quarter  of  an  hour  to  form 

122 


GLYCERINE   RECOVERY 

an  even  emulsion,  in  which  state  the  mass  is  kept  by  stirring 
occasionally  with  air  while  the  saponification  is  taking 
place.  A  temperature  is  maintained  a  degree  or  two  above 
the  titer  point  of  the  fat  with  closed  steam  which  may 
be  aided  by  covering  the  tank  for  a  period  of  24  to  48 
hours.  The  splitting  takes  place  rapidly  at  first,  then  pro- 
ceeds more  slowly.  In  24  hours  80  per  cent,  of  the  fats  are 
split  and  in  48  hours  85  per  cent,  to  90  per  cent. 

When  the  cleavage  has  reached  the  desired  point  the 
mass  is  heated  to  80  degrees-85  degrees  C.  with  live  or 
indirect  steam  while  stirring  with  air.  Then  0.1  per  cent- 
0.15  per  cent  of  concentrated  sulfuric  acid  diluted  with 
water  is  added  to  break  the  emulsion.  When  the  emulsion 
is  broken  the  glycerine  water  is  allowed  to  settle  out  and 
drawn  off.  The  glycerine  water  contains  12  per  cent, 
to  25  per  cent,  glycerine  and  contains  manganese  sulfate, 
sulfuric  acid  and  albuminous  matter.  Through  neutraliza- 
tion with  lime  at  boiling  temperature  and  filtration  the 
impurities  can  almost  all  be  removed  after  which  the 
glycerine  water  may  be  fed  to  the  evaporator.  Should  it  be 
desired  to  overcome  the  trouble  due  to  the  gypsum  formed 
in  the  glycerine,  the  lime  treatment  may  be  combined  with 
a  previous  treatment  of  the  glycerine  water  with  barium 
hydrate  to  remove  the  sulfuric  acid,  then  later  oxalic  acid 
to  precipitate  the  lime. 

The  fatty  acids  obtained  by  splitting  with  ferments  are  of 
very  good  color  and  adaptable  for  soap  making. 

KREBITZ    PROCESS. 

The  Krebitz  process  which  has  been  used  to  some  extent 
in  Europe  is  based  upon  the  conversion  of  the  fat  or  oil 
into  lime  soap  which  is  transformed  into  the  soda  soap  by 
the  addition  of  sodium  carbonate.  To  carry  out  the  process 
a  convenient  batch  of,  say,  10,000  pounds  of  fat  or  oil,  is  run 
into  a  shallow  kettle  containing  1,200  to  1,400  pounds  of  lime 

123 


SOAP-MAKING    MANUAL 

previously  slaked  with  3,700  to  4,500  pounds  of  water.  The 
mass  is  slowly  heated  with  live  steam  to  almost  boiling 
until  an  emulsion  is  obtained.  The  tank  is  then  covered 
and  allowed  to  stand  about  12  hours.  The  lime  soap  thus 
formed  is  dropped  from  the  tank  into  the  hopper  of  a 
mill,  finely  ground  and  conveyed  to  a  leeching  tank.  The 
glycerine  is  washed  out  and  the  glycerine  water  run  to  a 
tank  for  evaporation.  The  soap  is  then  further  washed 
and  these  washings  are  run  to  other  tanks  to  be  used  over 
again  to  wash  a  fresh  batch  of  soap.  About  150,000  pounds 
of  water  will  wash  the  soap  made  from  10,000  pounds  of 
fat  which  makes  between  15,000  and  16,000  pounds  of  soap. 
The  first  wash  contains  approximately  10  per  cent,  glycer- 
ine and  under  ordinary  circumstances  this  only  need  be 
evaporated  for  glycerine  recovery. 

After  extracting  the  glycerine  the  soap  is  slowly  intro- 
duced into  a  boiling  solution  of  sodium  carbonate  or  soda 
ash  and  boiled  until  the  soda  has  replaced  the  lime.  This 
fs  indicated  by  the  disappearance  of  the  small  lumps  of 
lime  soap.  Caustic  soda  is  then  added  to  saponify  the  fat 
not  converted  by  the  lime  saponification.  The  soap  is  then 
salted  out  and  allowed  to  settle  out  the  calcium  carbonate. 
This  drops  to  the  bottom  of  the  kettle  as  a  heavy  sludge 
entangling  about  10  per  cent,  of  the  soap.  A  portion  of 
this  soap  may  be  recovered  by  agitating  the  sludge  with 
heat  and  water,  pumping  the  soap  off  the  top  and  filtering 
the  remaining  sludge. 

While  the  soap  thus  obtained  is  very  good,  the  percent- 
age of  glycerine  recovered  is  greatly  increased  and  the 
cost  of  alkali  as  carbonate  is  less.  The  disadvantages  are 
many.  Large  quantities  of  lime  are  required;  it  is  difficult 
to  recover  the  soap  from  the  lime  sludge ;  the  operations  are 
numerous  prior  to  the  soap  making  proper  and  rather  com- 
plicated apparatus  is  required. 

124 


GLYCERINE    RECOVERY 

DISTILLATION    OF   FATTY    ACIDS. 

The  fatty  acids  obtained  by  various  methods  of  saponifi- 
cation  may  be  further  improved  by  distillation. 

In  order  to  carry  out  this  distillation,  two  methods  may 
be  pursued,  first,  the  continuous  method,  whereby  the 
fatty  acids  are  continually  distilled  for  five  to  six  days, 
and,  second,  the  two  phase  method,  whereby  the  distilla- 
tion continues  for  16  to  20  hours,  after  which  the  residue 
is  drawn  off,  treated  with  acid,  and  its  distillate  added 
to  a  fresh  charge  of  fatty  acids.  The  latter  method  is  by 
far  the  best,  since  the  advantages  derived  by  thus  pro- 
ceeding more  4than  compensate  the  necessity  of  cleaning 
the  still.  Better  colored  fatty  acids  are  obtained;  less 
unsaponifiable  matter  is  contained  therein;  there  is  no 
accumulation  of  impurities;  the  amount  of  neutral  fat 
is  lessened  because  the  treatment  of  the  tar  with  acid 
causes  a  cleavage  of  the  neutral  fat  and  the  candle  tar  or 
pitch  obtained  is  harder  and  better  and  thus  more  valu- 
able. 

The  stills  are  usually  built  of  copper,  which  are  heated  by 
both  direct  fire  and  superheated  steam.  Distillation  under 
vacuum  is  advisable.  To  begin  the  distilling  operation,  the 
still  is  first  filled  with  dry  hot  fatty  acids  to  the  proper 
level.  Superheated  steam  is  then  admitted  and  the  con- 
denser is  first  heated  to  prevent  the  freezing  of  the  fatty 
acids,  passing  over  into  same.  When  the  temperature 
reaches  230  deg.  C.  the  distillation  begins.  At  the  begin- 
ning, the  fatty  acids  flow  from  the  condensor,  an  intense 
green  color,  due  to  the  formation  of  copper  soaps  produced 
by  the  action  of  the  fatty  acids  on  the  copper  still.  This 
color  may  easily  be  removed  by  treating  with  dilute  acid 
to  decompose  the  copper  soaps. 

In  vacuum  distillation,  the  operation  is  begun  without 
125 


SOAP-MAKING    MANUAL 

the  use  of  vacuum.  Vacuum  is  introduced  only  when  the 
distillation  has  proceeded  for  a  time  and  the  introduction 
of  this  must  be  carefully  regulated,  else  the  rapid  influence 
of  vacuum  will  cause  the  contents  of  the  still  to  overflow. 
When  distillation  has  begun  a  constant  level  of  fatty  acids 
is  retained  therein  by  opening  the  feeding  valve  to  same, 
and  the  heat  is  so  regulated  as  to  produce  the  desired  rate 
of  distillation.  As  soon  as  the  distillate  flows  darker  and 
slower,  the  feeding  valve  to  the  still  is  shut  off  and  the 
distillation  continued  until  most  of  the  contents  of  the  still 
are  distilled  off,  which  is  indicated  by  a  rise  in  the  tempera- 
ture. Distillation  is  then  discontinued,  the  still  shut  down, 
and  in  about  an  hour  the  contents  are  sufficiently  cool  to 
be  emptied.  The  residue  is  run  off  into  a  proper  receiv- 
ing vessel,  treated  with  dilute  acid  and  used  in  the  distil- 
lation of  tar. 

In  the  distillation  of  tar  the  same  method  as  the  above 
is  followed,  only  distillation  proceeds  at  a  higher  tempera- 
ture. The  first  portion  and  last  portion  of  the  distillate 
from  tar  are  so  dark  that  it  is  necessary  to  add  them  to 
a  fresh  charge  of  fatty  acids.  By  a  well  conducted  distil- 
lation of  tar  about  50  per  cent,  of  the  fatty  acids  from  the 
tar  can  be  used  to  mix  with  the  distilled  fatty  acids.  The 
residue  of  this  operation  called  stearine  pitch  or  candle  tar 
consists  of  a  hard,  brittle,  dark  substance.  Elastic  pitch 
only  results  where  distillation  has  been  kept  constant  for 
several  days  without  interrupting  the  process,  and  re- 
distilling the  tar.  In  a  good  distillation  the  distillation 
loss  is  0.5  to  1.5%  and  loss  in  pitch  1.5%.  Fatty  acids 
which  are  not  acidified  deliver  about  3%  of  pitch.  Very 
impure  fats  yield  even  a  higher  percentage  in  spite  of 
acidifying.  For  a  long  time  it  was  found  impossible  to 
find  any  use  for  stearine  pitch,  but  in  recent  years  a  use 
has  been  found  for  same  in  the  electrical  installation  of 
cables. 

126 


CHAPTER    VI 

Analytical    Methods. 

While  it  is  possible  to  attain  a  certain  amount  of 
efficiency  in  determining  the  worth  of  the  raw  material 
entering  into  the  manufacture  of  soap  through  or- 
ganoleptic  methods,  these  are  by  no  means  accurate. 
It  is,  therefore,  necessary  to  revert  to  chemical  meth- 
ods to  correctly  determine  the  selection  of  fats,  oil  or 
other  substances  used  in  soap  making,  as  well  as  stand- 
ardizing a  particular  soap  manufactured  and  to  properly 
regulate  the  glycerine  recovered. 

It  is  not  our  purpose  to  cover  in  detail  the  numerous 
analytical  processes  which  may  be  employed  in  the  ex- 
amination of  fats  and  oils,  alkalis,  soap  and  glycerine, 
as  these  are  fully  and  accurately  covered  in  various 
texts,  but  rather  to  give  briefly  the  necessary  tests 
which  ought  to  be  carried  out  in  factories  where  large 
amounts  of  soap  are  made.  Occasion  often  arises  where 
it  is  impossible  to  employ  a  chemist,  yet  it  is  possible  to 
have  this  work  done  by  a  competent  person  or  to  have 
someone  instruct  himself  as  just  how  to  carry  out 
the  more  simple  analyses,  which  is  not  a  very  difficult 
matter.  The  various  standard  solutions  necessary  to 
carrying  out  the  simpler  titrations  can  readily  be  pur- 
chased from  dealers  in  chemical  apparatus  and  it  does 
not  take  extraordinary  intelligence  for  anyone  to  op- 
erate a  burette,  yet  in  many  soap  plants  in  this  country 
absolutely  no  attention  is  paid  to  the  examining  of  raw 
material,  though  many  thousand  pounds  are  handled 
annually,  which,  if  they  were  more  carefully  examined 
would  result  in  the  saving  of  much  more  money  than 

127 


SOAP-MAKING     MANUAL 

it  costs  to  examine  them  or  have  them  at  least  occa- 
sionally analyzed. 

ANALYSIS    OF    FATS    AND    OILS. 

In  order  to  arrive  at  proper  results  in  the  analysis 
of  a  fat  or  oil,  it  is  necessary  to  have  a  proper  sample. 
To  obtain  this  a  sample  of  several  of  the  packages  of 
oil  or  fat  is  taken  and  these  mixed  or  molten  together 
into  a  composite  sample  which  is  used  in  making  the 
tests.  If  the  oil  or  fat  is  solid,  a  tester  is  used  in  taking 
the  sample  from  the  package  and  if  they  are  liquid,  it 
is  a  simple  matter  to  draw  off  a  uniform  sample  from 
each  package  and  from  these  to  form  a  composite 
sample. 

In  purchasing  an  oil  or  fat  for  soap  making,  the  manu- 
facturer is  usually  interested  in  the  amount  of  free  fatty 
acid  contained  therein,  of  moisture,  the  titer,  the  per- 
centage of  unsaponifiable  matter  and  to  previously  de- 
termine the  color  of  soap  which  will  be  obtained  where 
color  is  an  object. 

DETERMINATION    OF    FREE    FATTY    ACIDS. 

Since  the  free  fatty  acid  content  of  a  fat  or  oil  represents 
a  loss  of  glycerine,  the  greater  the  percentage  of  free 
fatty  acid,  the  less  glycerine  is  contained  in  the  fat  or 
oil,  it  is  advisable  to  purchase  a  fat  or  oil  with  the  lower 
free  acid,  other  properties  and  the  price  being  the  same. 

While  the  mean  molecular  weight  of  the  mixed  free 
fatty  acids  varies  with  the  same  and  different  oils  or 
fats  and  should  be  determined  for  any  particular 
analysis  for  accuracy,  the  free  fatty  acid  is  usually  ex- 
pressed as  oleic  acid,  which  has  a  molecular  weight  of 
282. 

To  carry  out  the  analysis  5  to  20  grams  of  the  fat  are 

128 


ANALYTICAL   METHODS 

weighed  out  into  an  Erlenmeyer  flask  and  50  cubic  cen- 
timeters of  carefully  neutralized  alcohol  are  added.  In 
order  to  neutralize  the  alcohol  add  a  few  drops  of 
phenolphthalein  solution  to  same  and  add  a  weak 
caustic  soda  solution  drop  by  drop  until  a  very  faint 
pink  color  is  obtained  upon  shaking  or  stirring  the 
alcohol  thoroughly.  The  mixture  of  fat  and  neutralized 
alcohol  is  then  heated  to  boiling  and  titrated  with  tenth 
normal  alkali  solution,  using  phenolphthalein  as  an  in- 
dicator. As  only  the  free  fatty  acids  are  readily  soluble 
in  the  alcohol  and  the  fat  itself  only  slightly  mixes  with 
it,  the  flask  should  be  well  agitated  toward  the  end  of 
the  titration.  When  a  faint  pink  color  remains  after 
thoroughly  agitating  the  flask  the  end  point  is  reached. 
In  order  to  calculate  the  percentage  of  free  fatty  acid 
as  oleic  acid,  multiply  the  number  of  cubic  centimeters 
of  tenth  normal  alkali  used  as  read  on  the  burette  by 
0.0282  and  divide  by  the  number  of  grams  of  fat  taken 
for  the  determination  and  multiply  by  100. 

When  dark  colored  oils  or  fats  are  being  titrated  it  is 
often  difficult  to  obtain  a  good  end  point  with  phenolph- 
thalein. In  such  cases  about  2  cubic  centimeters  of  a 
2  per  cent,  alcoholic  solution  of  Alkali  Blue  6  B  is 
recommended. 

Another  method  of  directly  determining  the  free  fatty 
acid  content  of  tallow  or  grease  upon  which  this  de- 
termination is  most  often  made  is  to  weigh  out  into  an 
Erlenmeyer  flask  exactly  5.645  grams  of  a  sample  of 
tallow  or  grease.  Add  about  75  cubic  centimeters  of 
neutralized  alcohol.  Heat  until  it  boils,  then  titrate  with 
tenth  normal  alkali  and  divide  the  reading  by  2,  which 
gives  the  percentage  of  free  fatty  acid  as  oleic.  If  a 
fifth  normal  caustic  solution  i?  used,  the  reading  on  the 
burette  gives  the  percentage  of  free  fatty  acid  directly. 

129 


SOAP-MAKING    MANUAL 

This  method,  while  it  eliminates  the  necessity  of  calcula- 
tion, is  troublesome  in  that  it  is  difficult  to  obtain  the 
exact  weight  of  fat. 

MOISTURE. 

To  calculate  the  amount  of  moisture  contained  in  a  fat 
or  oil  5  to  10  grams  are  weighed  into  a  flat  bottom  dish, 
together  with  a  known  amount  of  clean,  dry  sand,  if  it 
is  so  desired.  The  dish  is  then  heated  over  a  water 
bath,  or  at  a  temperature  of  100-110  degs.  C.,  until  it 
no  longer  loses  weight  upon  drying  and  reweighing  the 
dish.  One  hour  should  elapse  between  the  time  the 
dish  is  put  on  the  water  bath  and  the  time  it  is  taken  off 
to  reweigh.  The  difference  between  the  weight  of  the 
dish  is  put  on  the  water  bath  and  the  time  it  is  taken  off 
when  it  reaches  a  constant  weight  is  moisture.  This 
difference  divided  by  the  original  weight  of  the  fat  or 
oil  X  100  gives  the  percentage  of  moisture. 

When  highly  unsaturated  fats  or  oils  are  being  ana- 
lyzed for  moisture,  an  error  may  be  introduced  either 
by  the  absorption  of  oxygen,  which  is  accelerated  at 
higher  temperature,  or  by  the  formation  of  volatile  fatty 
acids.  The  former  causes  an  increase  in  weight,  the 
latter  causes  a  decrease.  To  obviate  this,  the  above 
operation  of  drying  should  be  carried  out  in  the  pres- 
ence of  some  inert  gas  like  hydrogen,  carbon  dioxide, 
or  nitrogen. 

TITER. 

The  titer  of  a  fat  or  oil  is  really  an  indication  of  the 
amount  of  stearic  acid  contained  therein.  The  titer, 
expressed  in  degrees  Centigrade,  is  the  solidification  point 
of  the  fatty  acids  of  an  oil  or  fat.  In  order  to  carry  out  the 
operation  a  Centigrade  thermometer  graduated  in  one  or 
two-tenths  of  a  degree  is  necessary.  A  thermometer  grad- 

130 


ANALYTICAL   METHODS 

uated  between  10  degs.  centigrade  to  60  degs.  centi- 
grade is  best  adapted  and  the  graduations  should  be 
clear  cut  and  distinct. 

To  make  the  determination  about  30  grams  of  fat  are 
roughly  weighed  in  a  metal  dish  and  30-40  cubic  centi- 
meters of  a  30  per  cent.  (36  degs.  Baume)  solution  of 
sodium  hydroxide,  together  with  30-40  cubic  centimeters 
of  alcohol,  denatured  alcohol  will  do,  are  added  and  the 
mass  heated  until  saponified.  Heat  over  a  low  flame  or 
over  an  asbestos  plate  until  the  soap  thus  formed  is  dry, 
constantly  stirring  the  contents  of  the  dish  to  prevent 
burning.  The  dried  soap  is  then  dissolved  in  about  1000 
cubic  centimeters  of  water,  being  certain  that  all  the 
alcohol  has  been  expelled  by  boiling  the  soap  solution 
for  about  half  an  hour.  When  the  soap  is  in  solution 
add  sufficient  sulphuric  acid  to  decompose  the  soap,  ap- 
proximately 100  cubic  centimeters  of  25  degs.  Baume 
sulphuric  acid,  and  boil  until  the  fatty  acids  form  a  clear 
layer  on  top  of  the  liquid.  A  few  pieces  of  pumice  stone 
put  into  the  mixture  will  prevent  the  bumping  caused  by 
boiling.  Siphon  off  the  water  from  the  bottom  of  the 
dish  and  wash  the  fatty  acids  with  boiling  water 
until  free  from  sulphuric  acid.  Collect  the  fatty 
acids  in  a  small  casserole  or  beaker  and  dry  them  over 
a  steam  bath  or  drying  oven  at  110  degs.  Centigrade. 
When  the  fatty  acids  are  dry,  cool  them  to  about  10 
degs.  above  the  titer  expected  and  transfer  them  to  a 
titer  tube  or  short  test  tube  which  is  firmly  supported 
by  a  cork  in  the  opening  of  a  salt  mouth  bottle.  Hang 
the  thermometer  by  a  cord  from  above  the  supported 
tube  so  it  reaches  close  to  the  bottom  when  in  the  titer 
tube  containing  the  fatty  acids  and  so  that  it  may  be 
used  as  a  stirrer.  Stir  the  mass  rather  slowly,  closely 
noting  the  temperature.  The  temperature  will  grad- 

131 


SOAP-MAKING    MANUAL    . 

ually  fall  during  the  stirring  operation  and  finally  re- 
main stationary  for  half  a  minute  or  so  then  rise  from 
0.1  to  0.5  degs.  The  highest  point  to  which  the  mer- 
cury rises  after  having  been  stationary  is  taken  as  the 
reading  of  the  titer. 

DETERMINATION    OF    UNSAPONIFIABLE    MATTER. 

In  order  to  determine  the  unsaponifiable  matter  in 
fats  and  oils  they  are  first  saponified,  then  the  unsaponi- 
fiable, which  consists  mainly  of  hydrocarbons  and  the 
higher  alcohols  cholesterol  or  phytosterol,  is  extracted 
with  ether  or  petroleum  ether,  the  ether  evaporated 
and  the  residue  weighed  as  unsaponifiable. 

To  carry  out  the  process  first  saponify  about  5  grams 
of  fat  or  oil  with  an  excess  of  alcoholic  potassium  hy- 
drate, 20-30  cubic  centimeters  of  a  1  to  10  solution  of 
potassium  hydroxide  in  alcohol  until  the  alcohol  is 
evaporated  over  a  steam  bath.  Wash  the  soap  thus 
formed  into  a  separatory  funnel  of  200  cubic  centimeters 
capacity  with  80-100  cubic  centimeters  water.  Then 
add  about  60  cubic  centimeters  of  ether,  .petroleum 
ether  or  86  degs.  gasoline  and  thoroughly  shake  the  fun- 
nel to  extract  the  unsaponifiable.  Should  the  two  layers 
not  separate  readily,  add  a  few  cubic  centimeters  of 
alcohol,  which  will  readily  cause  them  to  separate. 
Draw  off  the  watery  solution  from  beneath  and  wash 
the  ether  with  water  containing  a  few  drops  of  sodium 
hydrate  and  run  to  another  dish.  Pour  the  watery  solu- 
tion into  the  funnel  again  and  repeat  the  extraction 
once  or  twice  more  or  until  the  ether  shows  no  dis- 
coloration. Combine  the  ether  extractions  into  the  fun- 
nel and  wash  with  water  until  no  alkaline  reaction  is 
obtained  from  the  wash  water.  Run  the  ether  extract 
to  a  weighed  dish,  evaporate  and  dry  rapidly  in  a  drying 

132 


ANALYTICAL   METHODS 

oven.  As  some  of  the  hydrocarbons  are  readily  volatile 
at  100  degs.  Centigrade,  the  drying  should  not  be  car- 
ried on  any  longer  than  necessary.  The  residue  is  then 
weighed  and  the  original  weight  of  fat  taken  divided 
into  the  weight  of  the  residue  X  100  gives  the  percentage 
unsaponifiable. 

TEST  FOR  COLOR  OF  SOAP. 

It  is  often  desirable  to  determine  the  color  of  the  fin- 
ished soap  by  a  rapid  determination  before  it  is  made 
into  soap.  It  often  happens,  especially  with  the  tallows, 
that  a  dark  colored  sample  produces  a  light  colored 
soap,  whereas  a  bleached  light  colored  tallow  produces 
a  soap  off  shade. 

To  rapidly  determine  whether  the  color  easily  washes 
out  of  the  tallow  with  lye,  100  cubic  centimeters  of  tal- 
low are  saponified  in  an  enameled  or  iron  dish  with 
100  cubic  centimeters  of  21  degs.  Baume  soda  lye  and 
100  cubic  centimeters  of  denatured  alcohol.  Continue 
heating  over  a  wire  gauze  until  all  the  alcohol  is  ex- 
pelled and  then  add  50  cubic  centimeters  of  the  21  degs. 
Baume  lye  to  grain  the  soap.  Allow  the  lyes  to  settle 
and  with  an  inverted  pipette  draw  off  the  lyes  into  a 
test  tube  or  bottle.  Close  the  soap  with  100  cubic  centi- 
meters of  hot  water  and  when  closed  again  grain  with 
50  cubic  centimeters  of  the  lye  by  just  bringing  to  a 
boil  over  an  open  flame.  Again  allow  the  lyes  to  settle 
and  put  aside  a  sample  of  the  lye  for  comparison.  Re- 
peat the  process  of  closing,  graining  and  settling  and 
take  a  sample  of  lye.  If  the  lye  is  still  discolored  re- 
peat the  above  operations  again  or  until  the  lye  is  color- 
less. Ordinarily  all  the  color  will  come  out  with  the 
third  lye.  The  soap  thus  obtained  contains  considerable 
water  which  makes  it  appear  white.  The  soap  is,  there- 
fore, dried  to  about  15  per  cent,  moisture  and  examined 

133 


SOAP-MAKING     MANUAL 

for  color.  The  color  thus  obtained  is  a  very  good  cri- 
terion as  to  what  may  be  expected  in  the  soap  kettle. 
By  making  the  above  analyses  of  fats  or  oils  the  main 
properties  as  to  their  adaptability  for  being  made  into 
soap  are  determined.  In  some  cases,  especially  where 
adulteration  or  mixtures  of  oils  are  suspected,  it  is  nec- 
essary to  further  analyze  same.  The  methods  of  carry- 
ing out  these  analyses  are  fully  covered  by  various  texts 
on  fats  and  oils  and  we  will  not  go  into  details  regard- 
ing the  method  of  procedure  in  carrying  these  out. 

TESTING    OF    ALKALIS    USED    IN    SOAP    MAKING. 

The  alkalis  entering  into  the  manufacture  of  soap  such 
as  caustic  soda  or  sodium  hydroxide,  caustic  potash  or 
potassium  hydrate,  carbonate  of  soda  or  sodium  carbonate, 
carbonate  of  potash  or  potassium  carbonate  usually  con- 
tain impurities  which  do  not  enter  into  combination  with 
the  fats  or  fatty  acids  to  form  soap.  It  is  out  of  the  ques- 
tion to  use  chemically  pure  alkalis  in  soap  making,  hence 
it  is  often  necessary  to  determine  the  alkalinity  of  an 
alkali.  It  may  again  be  pointed  out  that  in  saponifying  a 
neutral  fat  or  oil  only  caustic  soda  or  potash  are  efficient 
and  the  carbonate  contained  in  these  only  combines  to  a 
more  or  less  extent  with  any  free  fatty  acids  contained  in 
the  oils  or  fats.  Caustic  soda  or  potash  or  lyes  made 
from  these  alkalis  upon  exposure  to  the  air  are  grad- 
ually converted  into  sodium  or  potassium  carbonate  by 
the  action  of  the  carbon  dioxide  contained  in  the  air. 
While  the  amount  of  carbonate  thus  formed  is  not  very 
great  and  is  greatest  upon  the  surface,  all  lyes  as  well  as 
caustic  alkalis  contain  some  carbonate.  This  carbonate 
introduces  an  error  in  the  analysis  of  caustic  alkalis  when 
accuracy  is  required  and  thus  in  the  analysis  of  caustic 
soda  or  potash  it  is  necessary  to  remove  the  carbonate 

134 


ANALYTICAL   METHODS 

when  the  true  alkalinity  as  sodium  hydroxide  or  potas- 
sium hydroxide  is  desired.  This  may  be  done  by  titration 
in  alcohol  which  has  been  neutralized. 

In  order  to  determine  the  alkalinity  of  any  of  the  above 
mentioned  alkalis,  it  is  first  necessary  to  obtain  a  repre- 
sentative sample  of  the  substance  to  be  analyzed.  To  do 
this  take  small  samples  from  various  portions  of  the  pack- 
age and  combine  them  into  a  composite  sample.  Caustic 
potash  and  soda  are  hygroscopic  and  samples  should  be 
weighed  at  once  or  kept  in  a  well  stoppered  bottle.  Sodium 
or  potassium  carbonate  can  be  weighed  more  easily  as 
they  do  not  rapidly  absorb  moisture  from  the  air. 

To  weigh  the  caustic  soda  or  potash  place  about  five 
grams  on  a  watch  glass  on  a  balance  and  weigh  as  rapidly 
as  possible.  Wash  into  a  500  cubic  centimeter  volumetric 
flask  and  bring  to  the  mark  with  distilled  water.  Pipette 
off  50  cubic  centimeters  into  a  200  cubic  centimeter  beaker, 
dilute  slightly  with  distilled  water,  add  a  few  drops  of 
methyl  orange  indicator  and  titrate  with  normal  acid. 
For  the  carbonates  about  1  gram  may  be  weighed,  washed 
into  a  400  cubic  centimeter  beaker,  diluted  with  distilled 
water,  methyl  orange  indicator  added  and  titrated  with 
normal  acid.  It  is  advisable  to  use  methyl  orange  indi- 
cator in  these  titrations  as  phenolphthalein  is  affected  by 
the  carbon  dioxide  generated  when  an  acid  reacts  with  a 
carbonate  and  does  not  give  the  proper  end  point,  unless 
the  solution  is  boiled  to  expel  the  carbon  dioxide.  Litmus 
may  also  be  used  as  the  indicator,  but  here  again  it  is 
necessary  to  boil  as  carbon  dioxide  also  affects  this  sub- 
stance. As  an  aid  to  the  action  of  these  common  indica- 
tors the  following  table  may  be  helpful: 


135 


SOAP-MAKING    MANUAL 

Color  in          Color  in 
Indicator.  Acid  Alkaline  Action  of 

Solution.         Solution.  CO3. 

Methyl  orange        Red  Yellow      Very  slightly  acid 

Phenolphthalein      Colorless       Red  Acid 

Litmus  Red  Blue          Acid 

It  may  be  further  stated  that  methyl  orange  at  the  neu- 
tral point  is  orange  in  color. 

To  calculate  the  percentage  of  effective  alkali  from  the 
above  titrations,  it  must  be  first  pointed  out  that  in  the 
case  of  caustic  potash  or  soda  aliquoit  portions  are 
taken.  This  is  done  to  reduce  the  error  necessarily  in- 
volved by  weighing,  as  the  absorption  of  water  is  decided. 
Thus  we  had,  say,  exactly  5  grams  which  weighed  5.05 
grams  by  the  time  it  was  balanced.  This  was  dissolved 
in  500  cubic  centimeters  of  water  and  50  cubic  centimeters 
or  one  tenth  of  the  amount  of  the  solution  was  taken,  or 
in  each  50  cubic  centimeters  there  were  0.505  grams  of  the 
sample.  We  thus  reduced  the  error  of  weighing  by  one 
tenth  provided  other  conditions  introduce  no  errcr.  In 
the  case  of  the  carbonates  the  weight  is  taken  directly. 

One  cubic  centimeter  of  a  normal  acid  solution  is  the 
equivalent  of:  Grams. 

Sodium  Carbonate,  Na2CO3 0.05305 

Sodium  Hydroxide,  NaOH 0.04006 

Sodium  Oxide,  Na2O. 0.02905 

Carbonate  K2CO3 0.06908 

Potassium  Hydoxide,  KOH 0.05616 

Potassium  Oxide,  K20 0.04715 

Hence  to  arrive  at  the  alkalinity  we  multiply  the  num- 
ber of  cubic  centimeters,  read  on  the  burette,  by  the  factor 
opposite  the  terms  in  which  we  desire  to  express  the  al- 
kalinity, divide  the  weight  in  grams  thus  obtained  by  the 
original  weight  taken,  and  multiply  the  result  by  100, 

136 


ANALYTICAL   METHODS 

which  gives  the  percentage  of  alkali  in  the  proper  terms. 
For  example,  say,  we  took  the  0.505  grams  of  caustic 
potash  as  explained  above  and  required  8.7  cubic  centi- 
meter normal  acid  to  neutralize  the  solution,  then 

8.7  X  .05616  =  .4886  grams  KOH  in  sample 

.4886 

X  100  =  96.73%  KOH  in  sample. 

.505 

Caustic  potash  --often  contains  some  caustic  soda,  and 
while  it  is  possible  to  express  the  results  in  terms  of  KOH, 
regardless  of  any  trouble  that  may  be  caused  by  this  mix- 
ture in  soap  making,  an  error  is  introduced  in  the  results, 
not  all  the  alkali  being  caustic  potash.  In  such  cases  it  is 
advisable  to  consult  a  book  on  analysis  as  the  analysis 
is  far  more  complicated  than  those  given  we  will  not 
consider  it.  The  presence  of  carbonates,  as  already  stated, 
also  causes  an  error.  To  overcome  this  the  alkali  is  titrated 
in  absolute  alcohol,  filtering  off  the  insoluble  carbonate. 
The  soluble  portion  is  caustic  hydrate  and  may  be  titrated 
as  such.  The  carbonate  remaining  on  the  filter  paper  is 
dissolved  in  water  and  titrated  as  carbonate. 

SOAP  ANALYSIS. 

To  obtain  a  sample  of  a  cake  of  soap  for  analysis  is  a 
rather  difficult  matter  as  the  moisture  content  of  the  outer 
and  inner  layer  varies  considerably.  To  overcome  this 
difficulty  a  borer  or  sampler  may  be  run  right  through 
the  cake  of  soap,  or  slices  may  be  cut  from  various  parts 
of  the  cake,  or  the  cake  may  be  cut  and  run  through  a 
meat  chopper  several  times  and  mixed.  A  sufficient 
amount  of  a  homogeneous  sample  obtained  by  any  of  these 
methods  is  preserved  for  the  entire  analysis  by  keeping  the 
soap  in  a  securely  stoppered  bottle. 

The  more  important  determinations  of  soap  are  moist- 
ure, free  alkali,  or  fatty  acid,  combined  alkali  and  total 

137 


SOAP-MAKING     MANUAL 

fatty  matter.  Besides  these  it  is  often  necessary  to  de- 
termine insoluble  matter,  glycerine,  unsaponifiable  matter, 
rosin  and  sugar. 

MOISTURE. 

The  analysis  of  soap  for  moisture,  at  its  best,  is  most 
unsatisfactory,  for  by  heating  it  is  impossible  to  drive  off 
all  the  water,  and  on  the  other  hand  volatile  oils  driven 
off  by  heat  are  a  part  of  the  loss  represented  as  moisture. 

The  usual  method  of  determining  moisture  is  to  weigh 
2  to  3  grams  of  finely  shaved  soap  on  a  watch  glass  and 
heat  in  an  oven  at  105  degrees  C.  for  2  to  3  hours.  The 
loss  in  weight  is  represented  as  water,  although  it  is  really 
impossible  to  drive  off  all  the  water  in  this  way. 

To  overcome  the  difficulties  just  mentioned  either  the 
Smith  or  Fahrion  method  may  be  used.  Allen  recom- 
mends Smith's  method  which  is  said  to  be  truthful  to 
within  0.25  per  cent.  Fahrion's  method,  according  to 
the  author,  gives  reliable  results  to  within  0.5  per  cent. 
Both  are  more  rapid  than  the  above  manipulation.  To 
carry  out  the  method  of  Smith,  5  to  10  grams  of  finely 
ground  soap  are  heated  over  a  sand  bath  with  a  small 
Bunsen  flame  beneath  it,  in  a  large  porcelain  crucible. 
The  heating  takes  20  to  30  minutes,  or  until  no  further 
evidence  is  present  of  water  being  driven  off.  This  may 
be  tested  by  the  fogging  of  a  cold  piece  of  glass  held  over 
the  crucible  immediately  upon  removing  the  burner.  When 
no  fog  appears  the  soap  is  considered  dry.  Any  lumps  of 
soap  may  be  broken  up  by  a  small  glass  rod,  weighed  with 
the  crucible,  and  with  a  roughened  end  to  more  easily 
separate  the  lumps.  Should  the  soap  burn,  this  can  readily 
be  detected  by  the  odor,  which,  of  course,  renders  the 
analysis  useless.  The  loss  in  weight  is  moisture. 

138 


ANALYTICAL   METHODS 

By  Fahrion's  method*,  2  to  4  grams  of  soap  are  weighed 
in  a  platinum  crucible  and  about  three  times  its  weight, 
of  oleic  acid,  which  has  been  heated  at  120  degrees  C.  until 
all  the  water  is  driven  off  and  preserved  from  moisture,  " 
is  added  and  reweighed.  The  dish  is  then  cautiously 
heated  with  a  small  flame  until  all  the  water  is  driven  off 
and  all  the  soap  is  dissolved.  Care  must  be  exercised  not 
to  heat  too  highly  or  the  oleic  acid  will  decompose.  The  mo- 
ment the  water  is  all  driven  off  a  clear  solution  is  formed, 
provided  no  fillers  are  present  in  the  soap.  The  dish  is 
then  cooled  in  a  dessicator  and  reweighed.  The  loss  in 
weight  of  acid  plus  soap  is  moisture  and  is  calculated  on 
the  weight  of  soap  taken.  This  determination  takes  about 
fifteen  minutes. 

FREE    ALKALI    OR    ACID. 

(a)  Alcoholic  Method. 

Test  a  freshly  cut  surface  of  the  soap  with  a  few  drops 
of  an  alcoholic  phenolphthalein  solution.  If  it  does  not 
turn  red  it  may  be  assumed  free  fat  is  present;  should  a 
red  color  appear,  free  alkali  is  present.  In  any  case  dis- 
solve 2  to  5  grams  of  soap  in  100  cubic  centimeters  of 
neutralized  alcohol  and  heat  to  boiling  until  in  solution. 
Filter  off  the  undissolved  portion  containing  carbonate, 
etc.,  and  wash  with  alcohol.  Add  phenolphthalein  to  the 
filtrate  and  titrate  with  N/10  acid  and  calculate  the  per 
cent,  of  free  alkali  as  sodium  or  potassium  hydroxide. 
Should  the  filtrate  be  acid  instead  of  .alkaline,  titrate  with 
N/10  alkali  and  calculate  the  percentage  of  free  fatty  acid 
as  oleic  acid. 

The  insoluble  portion  remaining  on  the  filter  paper  is 
washed  with  water  until  all  the  carbonate  is  dissolved. 
The  washings  are  then  titrated  with  N/10  sulfuric  acid 
•Zeit.  Angew.  Chem.  19,  385  (1906). 

139 


SOAP-MAKING     MANUAL 

and  expressed  as  sodium  or  potassium  carbonate.  Should 
borates  or  silicates  be  present  it  is  possible  to  express  in 
terms  of  these.  If  borax  is  present  the  carbon  dioxide  is 
boiled  off  after  neutralizing  exactly  to  methyl  orange ;  cool, 
add  mannite  and  phenolphthalein  and  titrate  the  boric  acid 
with  standard  alkali. 

(b)   Bosshard  and  Huggenberg  Method.^ 

In  using  the  alcoholic  method  for  the  determination  of 
the  free  alkali  or  fat  in  soap  there  is  a  possibility  of  both 
free  fat  and  free  alkali  being  present.  Upon  boiling  in  an 
alcoholic  solution  the  fat  will  be  saponified,  thus  intro- 
ducing an  error  in  the  analysis.  The  method  of  Bosshard 
and  Huggenberg  overcomes  this  objection.  Their  method 
is  briefly  as  follows : 

Reagents. 

1.  N/10  hydrochloric  acid  to  standardize  N/10  alcoholic 
sodium  hydroxide. 

2.  Approximately   N/10  alcoholic   sodium   hydroxide   to 
fix  and  control  the  N/40  stearic  acid. 

3.  N/40  stearic  acid.     Preparation:    About  7.1  grams  of 
stearic  acid  are  dissolved  in  one  liter  of  absolute  alcohol, 
the  solution  filtered,  the  strength  determined  by  titration 
against   N/10  NaOH  and  then  protected  in  a  well  stop- 
pered   bottle,    or    better    still    connected    directly    to    the 
burette. 

4.  A  10  per  cent,  solution  of  barium  chloride.     Prepara- 
tion :     100  grams  of  barium  chloride  are  dissolved  in  one 
liter  of  distilled  water  and  filtered.     The  neutrality  of  the 
solution  should  be  proven  as  it  must  be  neutral. 

5.  a    naphtholphthalein    indicator    according    to    Soren- 
son.      Preparation :    0.1    gram    of    a    naphtholphthalein    is 
dissolved  in  150  cubic  centimeters  of  alcohol  and  100  cubic 


tZeit.   Angew.    Chem.    27,    11-20    (1914). 

140 


ANALYTICAL    METHODS 

centimeters   of   water.     For  every   10  cubic  centimeters  of 
liquid  use  at  least  12  drops  of  indicator. 

6.  Phenolphthalein   solution   1   gram  to   100  cubic  centi- 
meter 96  per  cent,  alcohol. 

7.  Solvent,  50  per  cent,  alcohol  neutralized. 

MANIPULATION. 

First — Determine  the  strength  of  the  N/10  alcoholic  so- 
dium hydroxide  in  terms  of  N/10  hydrochloric  acid  and 
calculate  the  factor,  e.  g. : 

10  c.c.  N/10  alcoholic  NaOH  =  9.95  N/10  HCI 

10  c.c.  N/10  alcoholic  NaOH  =  9.96  N/10  HCI 
The  alcoholic  N/10  NaOH  has  a  factor  of  0.996. 

Second — Control  the  N/40  stearic  acid  with  the  above 
alkali  to  obtain  its  factor,  e.  g. : 

40  c.c.  N/40  alcoholic  stearic  acid  — 

10.18  c.c.  N/10  NaOH] 

40  c.c.  N/40  alcoholic  stearic  acid  —  }•    10.2 

10.22  c.c.  N/10  NaOHJ 

10.2  X  F  N/10  NaOH  (0.996)  =  Factor  N/40  stearic  acid 
.'.Factor  N/40  stearic  acid  =  1.016. 

Third — About  5  grams  of  soap  are  weighed  and  dis- 
solved in  100  cubic  centimeters  of  50  per  cent,  neutralized 
alcohol  in  a  250  cubic  centimeter  Erlenmeyer  flask  over  a 
water  bath  and  connected  with  a  reflux  condenser.  When 
completely  dissolved,  which  takes  but  a  few  moments,  it 
is  cooled  by  allowing  a  stream  of  running  water  to  run 
over  the  outside  of  the  flask. 

Fourth — The  soap  is  precipitated  with  15  to  20  cubic 
centimeters  of  the  10  per  cent,  barium  chloride  solution. 

Fifth — After  the  addition  of  2  to  5  cubic  centimeters  of 
a  naphtholphthalein  solution  the  solution  is  titrated  with 
N/40  alcoholic  stearic  acid.  a  naphtholphthalein  is  red 
with  an  excess  of  stearic  acid.  To  mark  the  color  changes 

141 


SOAP-MAKING    MANUAL 

it  is  advisable  to  first  run  a  few  blanks  until  the  eye  has 
become  accustomed  to  the  change  in  the  indicator  in  the 
same  way.  The  change  from  green  to  red  can  then  be 
carefully  observed. 

Let  us  presume  5  grams  of  soap  were  taken  for  the 
analysis  and  20  cubic  centimeters  of  N/40  stearic  acid 
were  required  for  the  titration  then  to  calculate  the 
amount  of  NaOH  since  the  stearic  factor  is  1.016. 

20  X  1-016  =  20.32  N/40  stearic  acid  really  required. 

1  cubic  centimeter  N/40  stearic  acid  =  0.02  per  cent. 
NaOH  for  5  grams  soap. 

A  20.32  cubic  centimeters  N/40  stearic  acid  =  0.02  X 
20.32  per  cent.  NaOH  for  5  grams  soap. 

Hence  the  soap  contains  0.4064  per  cent.  NaOH. 

It  is  necessary,  however,  to  make  a  correction  by  this 
method.  When  the  free  alkali  amounts  to  over  0.1  per 
cent,  the  correction  is  -f-  0.01,  and  when  the  free  alkali 
exceeds  0.4  per  cent,  the  correction  is  +  0.04,  hence  in  the 
above  case  we  multiply  0.004064  by  0.04,  add  this  amount 
to  0.004064  and  multiply  by  100  to  obtain  the  true  per- 
centage. Should  the  alkalinity  have  been  near  0.1  per  cent. 
we  would  have  multiplied  by  0.01  and  added  this. 

If  carbonate  is  also  present  in  the  soap,  another  5  grams 
of  soap  is  dissolved  in  100  cubic  centimeters  of  50  per 
cent,  alcohol  and  the  solution  titrated  directly  after  cooling 
with  N/40  stearic  acid,  using  a  naphtholphthalein  or 
phenolphthalein  as  an  indicator,  without  the  addition  of 
barium  chloride.  From  the  difference  of  the  two  titra- 
tions  the  alkali  present  as  carbonate  is  determined. 

If  the  decomposed  soap  solution  is  colorless  with 
phenolphthalein,  free  fatty  acids  are  present,  which  may 
be  quickly  determined  with  alcoholic  N/10  sodium  hy- 
droxide. 

142 


ANALYTICAL   METHODS 

INSOLUBLE   MATTER. 

The  insoluble  matter  in  soap  may  consist  of  organic  or 
inorganic  substances.  Among  the  organic  substances  which 
are  usually  present  in  soap  are  oat  meal,  bran,  sawdust,  etc., 
while  among  the  common  inorganic  or  mineral  compounds 
are  pumice,  silex,  clay,  talc,  zinc  oxide,  infusorial  earth, 
sand  or  other  material  used  as  fillers. 

To  determine  insoluble  matter,  5  grams  of  soap  are  dis- 
solved in  75  cubic  centimeters  of  hot  water.  The  solution 
is  filtered  through  a  weighed  gooch  crucible  or  filter  paper. 
The  residue  remaining  on  the  filter  is  washed  >*ith  hot 
water  until  all  the  soap  is  removed,  is  then  dried  toVonstant 
weight  at  105  degrees  C.  and  weighed.  From  the  difference 
in  weight  of  the  gooch  or  filter  paper  and  the  dried  residue 
remaining  thereon  after  filtering  and  drying,  the  total  per- 
centage of  insoluble  matter  may  easily  be  calculated.  By 
igniting  the  residue  and  reweighing  the  amount  of  in- 
soluble mineral  matter  can  be  readily  determined. 

STARCH  AND  GELATINE. 

Should  starch  or  gelatine  be  present  in  soap  it  is  neces- 
sary to  extract  5  grams  of  the  soap  with  100  cubic  centi- 
meters of  95  per  cent,  neutralized  alcohol  in  a  Soxhlet  ex- 
tractor until  the  residue  on  the  extraction  thimble  is  in  a 
powder  form.  If  necessary  the  apparatus  should  be  discon- 
nected and  any  lumps  crushed,  as  these  may  contain  soap. 
The  residue  remaining  on  the  thimble  consists  of  all  sub- 
stances present  in  soap,  insoluble  in  alcohol.  This  is  dried 
and  weighed  so  that  any  percentage  of  impurities  not 
actually  determined  can  be  found  by  difference.  Starch  and 
gelatine  are  separated  from  carbonate,  sulfate  and  borate  by 
dissolving  the  latter  out  through  a  filter  with  cold  water.  The 
starch  and  gelatine  thus  remaining  can  be  determined  by 

143 


-i 


SOAP-MAKING     MANUAL 

own  methods,  starch  by  the  method  of  direct  hydrolysis1 
and  gelatine  by  Kjeldahling  and  calculating  the  correspond- 
ing amount  of  gelatine  from  the  percentage  of  nitrogen 
(17.9%)  therein.2 

TOTAL   FATTY   AND  RESIN   ACIDS. 

To  the  filtrate  from  the  insoluble  matter  add  40  cubic 
centimeters  of  half  normal  sulfurfc  acid,  all  the  acid  being 
added  at  once.  Boil,  stir  thoroughly  for  some  minutes  and 
keep  warm  on  a  water  bath  until  the  fatty  acids  have  col- 
lected as  a  clear  layer  on  the  surface.  Cool  by  placing  the 
beaker  in  ice  and  syphon  off  the  acid  water  through  a  filter. 
Should  the  fatty  acids  not  readily  congeal  a  weighed  amount 
of  dried  bleached  bees-wax  or  stearic  acid  may  be  added  to 
the  hot  mixture.  This  fuses  with  the  hot  mass  and  forms  a 
firm  cake  of  fatty  acids  upon  cooling.  Without  removing  the 
fatty  acids  from  the  beaker,  add  about  300  cubic  centimeters 
of  hot  water,  cool,  syphon  off  the  water  through  the  same 
filter  used  before  and  wash  again.  Repeat  washing,  cooling 
and  syphoning  processes  until  the  wash  water  is  no  longer 
acid.  When  this  stage  is  reached,  dissolve  any  fatty  acid 
which  may  have  remained  on  the  filter  with  hot  95  per  cent, 
alcohol  into  the  beaker  containing  the  fatty  acids.  Evap- 
orate the  alcohol  and  dry  the  beaker  to  constant  weight 
over  a  water  bath.  The  fatty  acids  thus  obtained  repre- 
sent the  combined  fatty  acids,  uncombined  fat  and 
hydrocarbons. 

DETERMINATION    OF   ROSIN. 

If  cesin  acids  are  present,  this  may  be  determined  by 
the  Lrebermann-Storch  reaction.  To  carry  out  this  test 
shake  2  'cubic  centimeters  of  the  fatty  acids  with  5  cubic 


1  Bull.    107,  Bur.   Chem.   U.   S.   Dept.   Agriculture. 
"Richards  and  Gies  Am.  J.   Physiol.    (1902)    7,   129. 

144 


ANALYTICAL   METHODS 

centimeters  of  acetic  anhydride;  warm  slightly;  cool;  draw 
off  the  anhydride  and  add  1 :1  sulfuric  acid.  A  violet 
color,  which  is  not  permanent,  indicates  the  presence  of 
rosin  in  the  soap.  The  cholesterol  in  linseed  or  fish  oil, 
which  of  course  may  be  present  in  the  soap,  also  give  this 
reaction. 

Should  resin  acids  be  present,  these  may  be  separated 
by  the  Twitchell  method,  which  depends  upon  the  difference 
in  the  behavior  of  the  fatty  and  resin  acids  when  con- 
verted into  their  ethyl  esters  through  the  action  of  hydro- 
chloric acid.  This  may  be  carried  out  as  follows : 

Three  grams  of  the  dried  mixed  acids  are  dissolved  in 
25  cubic  centimeters  of  absolute  alcohol  in  a  100  cubic 
centimeter  stoppered  flask ;  the  flask  placed  in  cold  water 
and  shaken.  To  this  cooled  solution  25  cubic  centimeters  of 
absolute  alcohol  saturated  with  dry  hydrochloric  acid  is 
added.  The  flask  is  shaken  occasionally  and  the  action 
allowed  to  continue  for  twenty  minutes,  then  10  grams  of 
dry  granular  zinc  chloride  are  added,  the  flask  shaken  and 
again  allowed  to  stand  for  twenty  minutes.  The  contents 
of  the  flask  are  then  poured  into  200  cubic  centimeters  of 
water  in  a  500  cubic  centimeter  beaker  and  the  flask  rinsed 
out  with  alcohol.  A  small  strip  of  zinc  is  placed  in 
the  beaker  and  the  alcohol  evaporated.  The  beaker  is 
then  cooled  and  transferred  to  a  separatory  funnel,  wash- 
ing out  the  beaker  with  50  cubic  centimeters  of  gasoline 
(boiling  below  80  degrees  C.)  and  extracting  by  shaking 
the  funnel  well.  Draw  off  the  acid  solution  after  allowing 
to  separate  and  wash  the  gasoline  with  water  until  -f ree 
from  hydrochloric  acid.  Draw  off  the  gasoline  solution 
and  evaporate  the  gasoline.  Dissolve  the  residue  in 
neutral  alcohol  and  titrate  with  standard  alkali  using 
phenolphthalein  as  an  indicator.  One  cubic  centimeter  of 
normal  alkali  equals  0.346  grams  of  rosin.  The  rosin  may 


SOAP-MAKING    MANUAL 

be  gravimetrically  determined  by  washing  the  gasoline  ex- 
tract with  water,  it  not  being  necessary  to  wash  absolutely 
free  from  acid,  then  adding  0.5  gram  of  potassium 
hydroxide  and  5  cubic  centimeters  of  alcohol  in  50  cubic 
centimeters  of  water.  Upon  shaking  the  resin  acids  are 
rapidly  saponified  and  extracted  by  the  dilute  alkaline  solu- 
tion as  rosin  soaps,  while  the  ethyl  esters  remain  in  solution 
in  the  gasoline.  Draw  off  the  soap  solution,  wash  the 
gasoline  solution  again  with  dilute  alkali  and  unite  the 
alkaline  solutions.  Decompose  the  alkaline  soap  solution  with 
an  excess  of  hydrochloric  acid  and  weigh  the  resin  acids, 
liberated  as  in  the  determination  of  total  fatty  acids. 

According  to  Lewkowitsch,  the  results  obtained  by  the 
volumetric  method  which  assumes  a  combining  weight  of 
346  for  resin  acids,  are  very  likely  to  be  high.  On  the 
other  hand  those  obtained  by  the  gravimetric  method  are 
too  low. 

Leiste  and  Stiepel1  have  devised  a  -simpler  method  for 
the  determination  of  rosin.  They  make  use  of  the  fact 
that  the  resin  acids  as  sodium  soaps  are  soluble  in  acetone 
and  particularly  acetone  containing  two  per  cent,  water, 
while  the  fatty  acid  soaps  are  soluble  in  this  solvent  to 
the  extent  of  only  about  2  per  cent.  First  of  all  it  is 
necessary  to  show  that  the  sample  to  be  analyzed  contains 
a  mixture  of  resin  and  fatty  acids.  This  may  be  done 
by  the  Liebermann-Storch  reaction  already  described. 
Glycerine  interferes  with  the  method.  Two  grams  of  fatty 
acids  or  3  grams  of  soap  are  weighed  in  a  nickel  crucible 
and  dissolved  in  15-20  cubic  centimeters  of  alcohol.  The 
solution  is  then  neutralized  with  alcoholic  sodium  hydroxide, 
using  phenolphthalein  as  an  indicator.  The  mass  is  con- 
centrated by  heat  over  an  asbestos  plate  until  a  slight  film 

1  Seifensieder  Ztg.  (1913)  No.  46. 
146 


ANALYTICAL   METHODS 

torms  over  it.  Then  about  10  grams  of  sharp,  granular, 
ignited  sand  are  stirred  in  by  means  of  a  spatula,  the 
alcohol  further  evaporated,  the  mixture  being  constantly 
stirred  and  then  thoroughly  dried  in  a  drying  oven.  The 
solvent  for  the  cooled  mass  is  acetone  containing  2  per 
cent,  water.  It  is  obtained  from  acetone  dried  by  ignited 
sodium  sulfate  and  adding  2  per  cent,  water  by  volume. 
One  hundred  cubic  centimeters  of  this  solvent  are  sufficient 
for  extracting  the  above.  The  extraction  of  the  rosin  soap 
is  conducted  by  adding  10  cubic  centimeters  of  acetone 
eight  times,  rubbing  the  mass  thoroughly  with  a  spatula 
and  decanting.  The  decanted  portions  are  combined  in  a 
beaker  and  the  suspended  fatty  soaps  allowed  to  separate. 
The  mixture  is  then  filtered  into  a  previously  weighed 
flask  and  washed  several  times  with  the  acetone  remaining. 
The  solution  of  rosin  soap  should  show  no  separation  of 
solid  matter  after  having  evaporated  to  half  the  volume 
and  allowing  to  cool.  If  a  separation  should  occur  another 
filtration  and  the  slightest  possible  washing  is  necessary. 
To  complete  the  analysis,  the  acetone  is  completely  evap- 
orated and  the  mass  dried  to  constant  weight  in  a  drying 
oven.  The  weight  found  gives  the  weight  of  the  rosin 
soap.  In  conducting  the  determination,  it  is  important  to 
dry  the  mixture  of  soap  and  sand  thoroughly.  In  dealing 
with  potash  soaps  it  is  necessary  to  separate  the  fatty 
acids  from  these  and  use  them  as  acetone  dissolves  too 
great  a  quantity  of  a  potash  soap. 

TOTAL   ALKALI. 

In  the  filtrate  remaining  after  having  washed  the  fatty 
acids  in  the  determination  of  total  fatty  and  resin  acids 
all  the  alkali  present  as  soap,  as  carbonate  and  as  hydroxide 
remains  in  solution  as  sulfate.  Upon  titrating  this  solu- 
tion with  half  normal  alkali  the  difference  between  the 

147 


SOAP-MAKING     MANUAL 

half  normal  acid  used  in  decomposing  the  soap  and  alkali 
used  in  titrating  the  excess  of  acid  gives  the  amount  of 
total  alkali  in  the  soap.  By  deducting  the  amount  of  free 
alkali  present  as  carbonate  or  hydroxide  previously  found 
the  amount  of  combined  alkali  in  the  soap  may  be 
^calculated. 

i  To   quickly    determine   total    alkali    in   soap    a    weighed 
^portion  of  the  soap  may  be  ignited  to  a  white  ash  and  the 
\&sh  titrated  for  alkalinity  using  methyl  orange  as   an  in- 
dicator. 

UNSAPONIFIED    MATTER. 

Dissolve  5  grams  of  soap  in  50  cubic  centimeters  of  50 
per  cent,  alcohol.  Should  any  free  fatty  acids  be  present 
neutralize  them  with  standard  alkali.  Wash  into  a  separa- 
tory  funnel  with  50  per  cent,  alcohol  and  extract  with 
100  cubic  centimeters  of  gasoline,  boiling  at  50  degrees  to 
60  degrees  C  Wash  the  gasoline  with  water,  draw  off  the 
watery  layer.  Run  the  gasoline  into  a  weighed  dish,  evap- 
orate the  alcohol,  dry  and  weigh  the  residue  as  unsaponi- 
fied  matter.  The  residue  contains  any  hydrocarbon  oils 
or  fats  not  converted  into  soap. 

SILICA    AND    SILICATES. 

The  insoluble  silicates,  sand,  etc.,  are  present  in  the 
ignited  residue  in  the  determination  of  insoluble  matter. 
Sodium  silicate,  extensively  used  as  a  filler,  however,  will 
only  show  itself  in  forming  a  pasty  liquid.  Where  it  is 
desired  to  determine  sodium  silicate,  10  grams  of  soap  are 
ashed  by  ignition,  hydrochloric  acid  added  to  the  ash  in 
excess  and  evaporated  to  dryness.  More  hydrochloric  acid 
is  then  added  and  the  mass  is  again  evaporated  until  dry; 
then  cooled;  moistened  with  hydrochloric  acid;  dissolved 
in  water;  filtered;  washed;  the  filtrate  evaporated  to  dry- 
ness  and  again  taken  up  with  hydrochloric  acid  and  water ; 

148 


ANALYTICAL   METHODS 

filtered  and  washed.  The  precipitates  are  then  combined 
and  ignited.  Silicon  dioxide  (SiO2)  is  thus  formed,  which 
can  be  calculated  to  sodium  silicate  (Na2Si4O»).  Should 
other  metals  than  alkali  metals  be  suspected  present  the 
filtrate  from  the  silica  determinations  should  be  examined. 

GLYCERINE  IN   SOAP. 

To  determine  the  amount  of  glycerine  contained  in  soa 
dissolve  25  grams  in  hot  water,  add  a  slight  excess*  o 
sulfuric  acid  and  keep  hot  until  the  fatty  acids  form  as 
clear  layer  on  top.  Cool  the  mass  and  remove  the  fat 
acids.  Filter  the  acid  solution  into  a  25  cubic  centimeter 
graduated  flask ;  bring  to  the  mark  with  water  and  de- 
termine the  glycerine  by  the  bichromate  method  as  de- 
scribed under  glycerine  analysis. 

When  sugar  is  present  the  bichromate  would  be  reduced 
by  the  sugar,  hence  this  method  is  not  applicable.  In  this 
case  remove  the  fatty  acids  as  before,  neutralize  an  aliquot 
portion  with  milk  of  lime,  evaporate  to  10  cubic  centi- 
meters, add  2  grams  of  sand  and  milk  of  lime  containing 
about  2  grams  of  calcium  hydroxide  and  evaporate  almost 
to  dryness.  Treat  the  moist  residue  with  5  cubic  centi- 
meters of  96  per  cent,  alcohol,  rub  the  whole  mass  into  a 
paste,  then  constantly  stirring,  heat  on  a  water  bath  and 
decant  into  a  250  cubic  centimeter  graduated  flask.  Re- 
peat the  washing  with  5  cubic  centimeters  of  alcohol  five 
or  six  times,  each  time  pouring  the  washings  into  the 
flask;  cool  the  flask  to  room  temperature  and  fill  to  the 
mark  with  96  per  cent,  alcohol,  agitate  the  flask  until  well 
mixed  and  filter  through  a  dry  filter  paper.  Take  200  cubic 
centimeters  of  the  filtrate  and  evaporate  to  a  syrupy  con- 
sistency over  a  safety  water  bath.  Wash  the  liquor  into 
a  stoppered  flask  with  20  cubic  centimeters  of  absolute 
alcohol,  add  30  cubic  centimeters  of  absolute  ether  10 

149 


SOAP-MAKING    MANUAL 

cubic  centimeters  at  a  time,  shaking  well  after  each  addi- 
tion and  let  stand  until  clear.  Pour  off  the  solution 
through  a  filter  into  a  weighed  dish  and  wash  out  the 
flask  with  a  mixture  of  three  parts  absolute  ether  and  two 
parts  absolute  alcohol.  Evaporate  to  a  syrup,  dry  for  one 
hour  at  the  temperature  of  boiling  water,  weigh,  ignite 
and  weigh  again.  The  loss  is  glycerine.  This  multiplied 
by  5/4  gives  the  total  loss  for  the  aliquot  portion  taken. 
The  glycerine  may  also  be  determined  by  the  acetin  or 
bichromate  methods  after  driving  off  the  alcohol  and  ether 
if  so  desired. 

SUGAR    IN    SOAP. 

To  determine  sugar  in  soap,  usually  present  in  trans- 
parent soaps,  decompose  a  soap  solution  of  5  grams  of 
soap  dissolved  in  100  cubic  centimeters  of  hot  water  with 
an  excess  of  hydrochloric  acid  and  separate  the  fatty  acids 
as  usual.  Filter  the  acid  solution  into  a  graduated  flask 
and  make  up  to  the  mark.  Take  an  aliquot  containing 
approximately  1  per  cent,  of  reducing  sugar  and  determine 
the  amount  of  sugar  by  the  Soxhlet  method.1 

GLYCERINE    ANALYSIS. 

The  methods  of  analyzing  glycerine  varied  so  greatly 
due  to  the  fact  that  glycerine  contained  impurities  which 
acted  so  much  like  glycerine  as  to  introduce  serious  errors 
in  the  determinations  of  crude  glycerine.  This  led  to  the 
appointment  of  committees  in  the  United  States  and 
Europe  to  investigate  the  methods  of  glycerine  analysis. 
An  international  committee  met  after  their  investigations 
and  decided  the  acetin  method  should  control  the  buying 
and  selling  of  glycerine,  but  the  more  convenient 
bichromate  method  in  a  standardized  form  might  be  used 


1  Bull   107,  Bur.   Chem.  U.  S.  Dept.  Agriculture. 
150 


ANALYTICAL   METHODS 

in  factory  control  and  other  technical  purposes.  The 
following  are  the  methods  of  analysis  and  sampling  as 
suggested  by  the  international  committee : 

SAMPLING. 

The  most  satisfactory  method  available  for  sampling 
crude  glycerine  liable  to  contain  suspended  matter,  or 
which  is  liable  to  deposit  salt  on  settling,  is  to  have  the 
glycerine  sampled  by  a  mutually  approved  sampler  as  soon 
as  possible  after  it  is  filled  into  drums,  but  in  any  case  be- 
fore any  separation  of  salt  has  taken  place.  In  such  cases 
he  shall  sample  with  a  sectional  sampler  (see  appendix) 
then  seal  the  drums,  brand  them  with  a  number  for 
identification,  and  keep  a  record  of  the  brand  number. 
The  presence  of  any  visible  salt  or  other  suspended  mat- 
ter is  to  be  noted  by  the  sampler,  and  a  report  of  the  same 
made  in  his  certificate,  together  with  the  temperature  of 
the  glycerine.  Each  drum  must  be  sampled.  Glycerine 
which  has  deposited  salt  or  other  solid  matter  cannot  be 
accurately  sampled  from  the  drums,  but  an  approximate 
sample  can  be  obtained  by  means  of  the  sectional  sampler, 
which  will  allow  a  complete  vertical  section  of  the  glycerine 
to  be  taken  including  any  deposit. 

ANALYSIS. 

1.  Determination  of  Free  Caustic  Alkali. — Put  20  grams 
of  the  sample  into   a    100  cc.   flask,   dilute  with  approx- 
imately 50  cc.   of  freshly  boiled   distilled   water,   add   an 
excess    of    neutral    barium    chloride    solution,    1    cc.    of 
phenolphthalein  solution,  make  up  to  the  mark  and  mix. 
Allow  the  precipitate  to  settle,  draw  off  50  cc.  of  the  clear 
liquid  and  titrate  with  normal  acid  (AVI).     Calculate  the 
percentage  of  Na2O  existing  as  caustic  alkali. 

2.  Determination  of  Ash  and  Total  Alkalinity. — Weigh 

151 


SOAP-MAKING    MANUAL 

2  to  5  grams  of  the  sample  in  a  platinum  dish,  burn  off  the 
glycerine  over  a  luminous  Argand  burner  or  other  source 
of  heat,1  giving  a  low  temperature,  to  avoid  volatilization 
and  the  formation  of  sulphides.  When  the  mass  is  charred 
to  the  point  that  water  will  not  be  colored  by  soluble  or- 
ganic matter,  lixiviate  with  hot  distilled  water,  filter,  wash 
and  ignite  the  residue  in  the  platinum  dish.  Return  the 
filtrate  and  washings  to  the  dish,  evaporate  the  water,  and 
carefully  ignite  without  fusion.  Weigh  the  ash. 

Dissolve  the  ash  in  distilled  water  and  titrate  total  al- 
kalinity, using  as  indicator  methyl  orange  cold  or  litmus 
boiling. 

3.  Determination  of  Alkali  Present  as  Carbonate. — Take 
10  grams  of  the  sample,  dilute  with  50  cc.  distilled  water, 
add  sufficient  N/l  acid  to  neutralize  the  total  alkali  found 
at  (2),  boil  under  a  reflux  condenser  for  15  to  20  minutes, 
wash  down  the  condenser  tube  with  distilled  water,  free 
from   carbon   dioxide,   and    then    titrate    back    with  N/l 
NaOH,  using  phenolphthalein  as   indicator.     Calculate  the 
percentage  of  Na,.O.    Deduct  the  Na^O  found  in  (1).     The 
difference  is  the  percentage  of  Na2O  existing  as  carbonate. 

4.  Alkali  Combined  with  Organic  Acids. — The  sum  of 
the  percentages  of  Na2O  found  at   (1)   and   (3)   deducted 
from  the  percentage   found   at    (2)    is   a  measure  of  the 
Na2O  or  other  alkali  combined  with  organic  acids. 

5.  Determination    of   Acidity. — Take    10    grams    of   the 
sample,  dilute  with  50  cc.  distilled  water  free  from  carbon 
dioxide,  and  titrate  with  N/l  NaOH  and  phenolphthalein. 
Express  in  terms  of  Na2O  required  to  neutralize  100  grams. 

6.  Determination  of  Total  Residue  at  160°  C. — For  this 
determination  the  crude  glycerine  should  be  slightly  alka- 
line  with   Na2COs   not  exceeding  0.2  per   cent.    Na2O,   in 

1  Carbon  is  readily  burned  off  completely,  without  loss  of  chlor- 
ides, in  a  gas-heated  muffle  furnace  adjusted  to  a  dull  rtd  heat. 

152 


ANALYTICAL  METHODS 

order  to  prevent  loss  of  organic  acids.  To  avoid  the  for- 
mation of  polyglycerols  this  alkalinity  must  not  be  ex- 
ceeded. 

Ten  grams  of  the  sample  are  put  into  a  100  cc.  flask, 
diluted  with  water  and  the  calculated  quantity  of  N/l 
HC1  or  Na2CO3  added  to  give  the  required  degree  of 
alkalinity.  The  flask  is  filled  to  100  cc.,  the  contents 
mixed,  and  10  cc.  measured  into  a  weighed  Petrie  or 
similar  dish  2.S  in.  in  diameter  and  0.5  in.  deep,  which 
should  have  a  flat  bottom.  In  the  case  of  crude  glycerine 
abnormally  high  in  organic  residue  a  smaller  amount 
should  be  taken,  so  that  the  weight  of  the  organic  residue 
does  not  materially  exceed  30  to  40  milligrams. 

The  dish  is  placed  on  a  water  bath  (the  top  of  the  160° 
oven  acts  equally  well)  until  most  of  the  water  has  evap- 
orated. From  this  point  the  evaporation  is  effected  in 
the  oven.  Satisfactory  results  are  obtained  in  an  oven1 
measuring  12  ins.  cube,  having  an  iron  plate  0.75  in.  thick 
lying  on  the  bottom  to  distribute  the  heat.  Strips  of  ab- 
bestos  millboard  are  placed  on  a  shelf  half  way  up  the 
oven.  On  these  strips  the  dish  containing  the  glycerine 
is  placed. 

If  the  temperature  of  the  oven  has  been  adjusted  to 
160°  C.  with  the  door  closed,  a  temperature  of  130°  to 
140°  can  be  readily  maintained  with  the  door  partially 
open,  and  the  glycerine,  or  most  of  it,  should  be  evap- 
orated off  at  this  temperature.  When  only  a  slight 
vapor  is  seen  to  come  off,  the  dish  is  removed  and  allowed 
to  cool. 

An  addition  of  0.5  to  1.0  cc.  of  water  is  made,  and  by 

1  An  electric  oven  suitable  for  this  work,  which  is  readily  ad- 
justed to  160  degs.  C.,  has  been  made  for  Mr.  Low  and  the  chair- 
man, by  the  Apparatus  and  Specialty  Company,  Lansing,  Mich. 
Its  size  is  9*4  x  10  x  16  inches,  and  capacity  8  Petrie  dishes.  It 
gives  a  strong  draft  at  constant  temperature. 

151 


SOAP-MAKING     MANUAL 

a  rotary  motion  the  residue  brought  wholly  or  nearly 
into  solution.  The  dish  is  then  allowed  to  remain  on  a 
water  bath  or  top  of  the  oven  until  the  excess  water  has 
evaporated  and  the  residue  is  in  such  a  condition  that 
on  returning  to  the  oven  at  160°  C.  it  will  not  spurt.  The 
time  taken  up  to  this  point  cannot  be  given  definitely,  nor 
is  it  important.  Usually  two  or  three  hours  are  required. 
From  this  point,  however,  the  schedule  of  time  must  be 
strictly  adhered  to.  The  dish  is  allowed  to  remain  in 
the  oven,  the  temperature  of  which  is  carefully  main- 
tained at  160°  C.  for  one  hour,  when  it  is  removed, 
cooled,  the  residue  treated  with  water,  and  the  water 
evaporated  as  before.  The  residue  is  then  subjected  to 
a  second  baking  of  one  hour,  after  which  the  dish  is 
allowed  to  cool  in  a  desiccator  over  sulphuric  acid  and 
weighed.  The  treatment  with  water,  etc.,  is  repeated 
until  a  constant  loss  of  1  to  1.5  mg.  per  hour  is  obtained. 

In  the  case  of  acid  glycerine  a  correction  must  be 
made  for  the  alkali  added  1  cc.  N/l  alkali  represents  an 
addition  of  0.03  gram.  In  the  case  of  alkaline  crudes  a 
correction  should  be  made  for  the  acid  added.  Deduct 
the  increase  in  weight  due  to  the  conversion  of  the 
NaOH  and  Na2CO3  to  NaCl.  The  corrected  weight 
multiplied  by  100  gives  the  percentage  of  total  residue 
at  160°  C. 

This  residue  is  taken  for  the  determination  of  the 
non-volatile  acetylizable  impurities  (see  acetin  method). 

7.  Organic  residue. — Subtract  the  ash  from  the  total 
residue  at  160°  C.  Report  as  organic  residue  at  160°  C. 
(it  should  be  noted  that  alkaline  salts  of  fatty  acids  are 
converted  to  carbonates  on  ignition  and  that  the  CO. 
thus  derived  is  not  included  in  the  organic  residue). 

154 


ANALYTICAL  METHODS 

ACETIN   PROCESS  FOR  THE  DETERMINATION   OF  GLYCEROL. 

This  process  is  the  one  agreed  upon  at  a  conference  of 
delegates  from  the  British,  French,  German  and  American 
committees,  and  has  been  confirmed  by  each  of  the  above 
committees  as  giving  results  nearer  to  the  truth  than  the 
bichromate  method  on  crudes  in  general.  It  is  the  process 
to  be  used  (if  applicable)  whenever  only  one  method  is 
employed.  On  pure  glycerines  the  results  are  identical 
with  those  obtained  by  the  bichromate  process.  For  the 
application  of  this  method  the  crude  glycerine  should  not 
contain  over  60  per  cent,  water. 

REAGENTS    REQUIRED. 

(A)  Best  Acetic  Anhydride. — This  should  be  carefully 
selected.  A  good  sample  must  not  require  more  than  0.1 
cc.  normal  NaOH  for  saponification  of  the  impurities  when 
a  blank  is  run  on  7.5  cc.  Only  a  slight  color  should  de- 
velop during  digestion  of  the  blank. 

The  anhydride  may  be  tested  for  strength  by  the  fol- 
lowing method:  Into  a  weighed  stoppered  vessel,  con- 
taining 10  to  20  cc.  of  water,  run  about  2  cc.  of  the  anhy- 
dride, replace  the  stopper  and  weigh.  Let  stand  with  oc- 
cassional  shaking,  for  several  hours,  to  permit  the  hydro- 
lysis of  all  the  anhydride ;  then  dilute  to  about  200  cc.,  add 
phenolphthalein  and  titrate  with  AVI  NaOH.  This  gives 
the  total  acidity  due  to  free  acetic  acid  and  acid  formed 
from  the  anhydride.  It  is  worthy  of  note  that  in  the 
presence  of  much  free  anhydride  a  compound  is  formed 
with  phenolphthalein,  soluble  in  alkali  and  acetic  acid,  but 
insoluble  in  neutral  solutions.  If  a  turbidity  is  noticed 
toward  the  end  of  the  neutralization  it  is  an  indication  that 
the  anhydride  is  incompletely  hydrolyzed  and  inasmuch  as 
the  indicator  is  withdrawn  from  the  solution,  results  may 
be  incorrect 

155 


SOAP-MAKING    MANUAL 

Into  a  stoppered  weighing  bottle  containing  a  known 
weight  of  recently  distilled  aniline  (from  10  to  20  cc.) 
measure  about  2  cc.  of  the  sample,  stopper,  mix,  cool  and 
weigh.  Wash  the  contents  into  about  200  cc.  of  cold  water, 
and  titrate  the  acidity  as  before.  This  yields  the  acidity 
due  to  the  original,  preformed,  acetic  acid  plus  one-half 
the  acid  due  to  anhydride  (the  other  half  having  formed 
acetanilide)  ;  subtract  the  second  result  from  the  first 
(both  calculated  to  100  grams)  and  double  the  result,  ob- 
taining the  cc.  N/l  NaOH  per  100  grams  of  the  sample. 
1  cc.  Af/NaOH  equals  0.0510  anhydride. 

(B)  Pure  Fused  Sodium  Acetate. — The  purchased  salt 
is  again  completely  fused  in  a  platinum,  silica  or  nickel 
dish,  avoiding  charring,  powdered  quickly  and  kept  in  a 
stoppered  bottle  or  desiccator.     It  is  most  important  that 
the  sodium  acetate  be  anhydrous. 

(C)  A  Solution  of  Caustic  Soda  for  Neutralising,  of 
about  N/l  Strength,  Free  from  Carbonate. — This  can  be 
readily  made  by  dissolving  pure  sodium  hydroxide  in  its 
own  weight  of  water  (preferably  water  free  from  carbon 
dioxide)    and  allowing  to   settle  until  clear,    or    filtering 
through  an  asbestos  or  paper  filter.    The  clear  solution  is 
diluted  with  water  free  from  carbon  dioxide  to  the  strength 
required.  „ 

(D)  N/l    Caustic    Soda   Free    from    Carbonate. — Pre- 
pared as  above  and  carefully  standardized.     Some  caustic 
soda  solutions  show  a  marked  diminution  in  strength  after 
being  boiled;  such  solutions  should  be  rejected. 

(£)    N/l  Acid. — Carefully  standardized. 
(F)    Phenolphthalein  Solution. — 0.5    per    cent,    phenol- 
phthalein  in  alcohol  and  neutralized. 

THE    METHOD. 

In    a    narrow-mouthed    flask     (preferably    round-bot- 
156 


ANALYTICAL   METHODS 

tomed),  capacity  about  120  cc.,  which  has  been  thoroughly 
cleaned  and  dried,  weigh  accurately  and  as  rapidly  as  pos- 
sible 1.25  to  1.5  grams  of  the  glycerine.  A  Grethan  or 
Lunge  pipette  will  be  found  convenient.  Add  about  3 
grams  of  the  anhydrous  sodium  acetate,  then  7.5  cc.  «f  the 
acetic  anhydride,  and  connect  the  flask  with  an  upright 
Liebig  condenser.  For  convenience  the  inner  tube  of  this 
condenser  should  not  be  over  50  cm.  long  and  9  to  10  mm. 
inside  diameter.  The  flask  is  connected  to  the  condenser 
by  either  a  ground  glass  joint  (preferably)  or  a  rubber 
stopper.  If  a  rubber  stopper  is  used  it  should  have  had  a 
preliminary  treatment  with  hot  acetic  anhydride  vapor. 

Heat  the  contents  and  keep  just  boiling  for  one  hour, 
taking  precautions  to  prevent  the  salts  drying  on  the  sides 
of  the  flask. 

Allow  the  flask  to  cool  somewhat,  and  through  the  con- 
denser tube  add  50  cc.  of  distilled  water  free  from  carbon 
dioxide  at  a  temperature  of  about  80°  C,  taking  care  that 
the  flask  is  not  loosened  from  the  condenser.  The  object 
of  cooling  is  to  avoid  any  sudden  rush  of  vapors  from  the 
flask  on  adding  water,  and  to  avoid  breaking  the  flask. 
Time  is  saved  by  adding  the  water  before  the  contents  of 
the  flask  solidify,  but  the  contents  may  be  allowed  to  solid- 
ify and  the  test  proceeded  with  the  next  day  without  detri- 
ment, bearing  in  mind  that  the  anhydride  in  excess  is  much 
more  effectively  hydrolyzed  in  hot  than  in  cold  water.  The 
contents  of  the  flask  may  be  warmed  to,  but  must  not  ex- 
ceed, 80°  C.,  until  the  solution  is  complete,  except  a  few 
dark  flocks  representing  organic  impurities  in  the  crude. 
By  giving  the  flask  a  rotary  motion,  solution  is  more 
quickly  effected. 

Cool  the  flask  and  contents  without  loosening  from  the 
condenser.  When  quite  cold  wash  down  the  inside  of  the 
condenser  tube,  detach  the  flask,  wash  off  the  stopper  or 

157 


SOAP-MAKING    MANUAL 

ground  glass  connection  into  the  flask,  and  filter  the  contents 
through  an  acid-washed  filter  into  a  Jena  glass  flask  of 
about  1  litre  capacity.  Wash  thoroughly  with  cold  distilled 
water  free  from  carbon  dioxide.  Add  2  cc.  of  phenol- 
phthalein  solution  (F),  then  run  in  caustic  soda  solution 
(C)  or  (D)  until  a  faint  pinkish  yellow  color  appears 
throughout  the  solution.  This  neutralization  must  be  done 
most  carefully ;  the  alkali  should  be  run  down  the  sides  of 
the  flask,  the  contents  of  which  are  kept  rapidly  swirling 
with  occasional  agitation  or  change  of  motion  until  the 
solution  is  nearly  neutralized,  as  indicated  by  the  slower 
disappearance  of  the  color  developed  locally  by  the  alkali 
running  into  the  mixture.  When  this  point  is  reached 
the  sides  of  the  flask  are  washed  down  with  carbon 
dioxide-free  water  and  the  alkali  subsequently  added  drop 
by  drop,  mixing  after  each  drop  until  the  desired  tint 
is  obtained. 

Now  run  in  from  a  burette  50  cc.  or  a  calculated  excess 
of  N/l  NaOH  (L>)  and  note  carefully  the  exact  amount. 
Boil  gently  for  15  minutes,  the  flask  being  fitted  with  a 
glass  tube  acting  as  a  partial  condenser.  Cool  as  quickly 
as  possible  and  titrate  the  excess  of  NaOH  with  N/l  acid 
(E)  until  the  pinkish  yellow  or  chosen  end-point  color 
just  remains.1  A  further  addition  of  the  indicator  at  this 
point  will  cause  an  increase  of  the  pink  color;  this  must 
be  neglected,  and  the  first  end-point  taken. 

From  the  N/l  NaOH  consumed  calculate  the  percentage 
of  glycerol  (including  acetylizable  impurities)  after  mak- 
ing the  correction  for  the  blank  test  described  below. 

1  cc.  N/l  NaOH  =  0.03069  gram  glycerol. 

The   coefficient    of    expansion    for    normal    solutions    is 

1A  precipitate  at  this  point  is  an  indication  of  the  presence  of 
iron  or  alumina,  and  high  results  will  be  obtained  unless  a  cor- 
rection is  made  as  described  below. 

158 


ANALYTICAL   METHODS 

0.00033  per  cc.  for  each  degree  centigrade.  A  correction 
should  be  made  on  this  account  if  necessary. 

Blank  Test. — As  the  acetic  anhydride  and  sodium  acetate 
may  contain  impurities  which  affect  the  result,  it  is  neces- 
sary to  make  a  blank  test,  using  the  same  quantities  of 
acetic  anhydride,  sodium  acetate  and  water  as  in  the  analy- 
sis. It  is  not  necessary  to  filter  the  solution  of  the  melt 
in  this  case,  but  sufficient  time  must  be  allowed  for  the 
hydrolysis  of  the  anhydride  before  proceeding  with  the 
neutralization.  After  neutralization  it  is  not  necessary  to 
add  more  than  10  cc.  of  the  N/l  alkali  (D),  as  this  repre- 
sents the  excess  usually  present  after  the  saponification 
of  the  average  soap  lye  crude.  In  determining  the  acid 
equivalent  of  the  N/l  NaOH,  however,  the  entire  amount 
taken  in  the  analysis,  50  cc.,  should  be  titrated  after  dilu- 
tion with  300  cc.  water  free  from  carbon  dioxide  and  with- 
out boiling. 

Determination  of  the  Glyccrol  Value  of  the  Acetylizable 
Impurities. — The  total  residue  at  160°  C.  is  dissolved  in 
1  or  2  cc.  of  water,  washed  into  the  acetylizing  flask  and 
evaporated  to  dryness.  Then  add  anhydrous  sodium  ace- 
tate and  acetic  anhydride  in  the  usual  amounts  and  proceed 
as  described  in  the  regular  analysis.  After  correcting  for 
the  blank,  calculate  the  result  to  glycerol. 

WAYS    OF    CALCULATING    ACTUAL    GLYCEROL    CONTENT. 

(1)  Determine  the  apparent  percentage  of  glycerol  in 
the  sample  by  the  acetin  process  as  described.    The  result 
will  include  acetylizable  impurities  if  any  are  present. 

(2)  Determine  the  total  residue  at  160°  C. 

(3)  Determine  the  acetin  value  of  the  residue  at   (2) 
in  terms  of  glycerol. 

(4)  Deduct  the  result  found  at  (3)   from  the  percent- 
age obtained  at    (1)    and  report  this  corrected  figure  as 

159 


SOAP-MAKING    MANUAL 

glycerol.      If   volatile   acetylizable    impurities    are    present 
these  are  included  in  this  figure. 

Trimethylenglycol  is  more  volatile  than  glycerine  and 
can  therefore  be  concentrated  by  fractional  distillation.  An 
approximation  to  the  quantity  can  be  obtained  from  the 
spread  between  the  acetin  and  bichromate  results  on  such 
distillates.  The  spread  multiplied  by  1.736  will  give  the 
glycol. 

BICHROMATE     PROCESS     FOR     GLYCEROL     DETERMINATION.         RE- 
AGENTS   REQUIRED. 

(A)  Pure  potassium  bichromate  powdered  and  dried 
in  air  free  from  dust  or  organic  vapors,  at  110°  to  120°  C. 
This  is  taken  as  the  standard. 

(5)  Dilute  Bichromate  Solution. — 7.4564  grams  of  the 
above  bichromate  are  dissolved  in  distilled  water  and  the 
solution  made  up  to  one  liter  at  15.5°  C. 

(C)  Ferrous   Ammonium   Sulphate. — It   is    never    safe 
to  assume  this  salt  to  be  constant  in  composition  and  it 
must  be  standardized  against  the  bichromate  as  follows : 
dissolve  3.7282  grams  of  bichromate  (A)  in  50  cc.  of  water. 
Add  50  cc.  of  50  per  cent,  sulphuric  acid  (by  volume),  and 
to  the  cold  undiluted  solution  add  from  a  weighing  bottle 
a  moderate  excess  of  the  ferrous  ammonium  sulphate,  and 
titrate  back  with   the   dilute   bichromate    (B).     Calculate 
the  value  of  the  ferrous  salt  in  terms  of  bichromate. 

(D)  Silver   Carbonate. — This   is   prepared   as   required 
for  each  test  from  140  cc.  of  0.5  per  cent,  silver  sulphate 
solution  by  precipitation,  with  about  4.9  cc.  N/l   sodium 
carbonate  solution   (a  little  less  than  the  calculated  quan- 
tity of  N/l  sodium  carbonate  should  be  used  as  an  excess 
to  prevent  rapid  settling).    Settle,  decant  and  wash  one  by 
decantation. 

(£)     Subacetate  of  Lead. — Boil  a  10  per  cent,  solution 
160 


ANALYTICAL  METHODS 

of  pure  lead  acetate  with  an  excess  of  litharge  for  one 
hour,  keeping  the  volume  constant,  and  filter  while  hot. 
Disregard  any  precipitate  which  subsequently  forms.  Pre- 
serve out  of  contact  with  carbon  dioxide. 

(J7)  Potassium  Ferricyanide. — A  very  dilute,  freshly 
prepared  solution  containing  about  0.1  per  cent. 

THE    METHOD. 

Weigh  20  grams  of  the  glycerine,  dilute  to  250  cc.  and 
take  25  cc.  Add  the  silver  carbonate,  allow  to  stand,  with 
occasional  agitation,  for  about  10  minutes,  and  add  a  slight 
excess  (about  5  cc.  in  most  cases)  of  the  basic  lead  acetate 
(£),  allow  to  stand  a  few  minutes,  dilute  with  distilled 
water  to  100  cc.,  and  then  add  0.15  cc.  to  compensate  for 
the  volume  of  the  precipitate,  mix  thoroughly,  filter  through 
an  air-dry  filter  into  a  suitable  narrow-mouthed  vessel,  re- 
jecting the  first  10  cc.,  and  return  the  filtrate  if  not  clear 
and  bright.  Test  a  portion  of  the  filtrate  with  a  little 
basic  lead  acetate,  which  should  produce  no  further  pre- 
cipitate (in  the  great  majority  of  cases  5  cc.  are  ample, 
but  occasionally  a  crude  will  be  found  requiring  more,  and 
in  this  case  another  aliquot  of  25  cc.  of  the  dilute  glycerine 
should  be  taken  and  purified  with  6  cc.  of  the  basic  acetate). 
Care  must  be  taken  to  avoid  a  marked  excess  of  basic 
acetate. 

Measure  off  25  cc.  of  the  clear  filtrate  into  a  flask  or 
beaker  (previously  cleaned  with  potassium  bichromate  and 
sulphuric  acid).  Add  12  drops  of  sulphuric  acid  (1  :  4) 
to  precipitate  the  small  excess  of  lead  as  sulphate.  Add 
3.7282  grams  of  the  powdered  potassium  bichromate  (A). 
Rinse  down  the  bichromate  with  25  cc.  of  water  and  let 
stand  with  occasional  shaking  until  all  the  bichromate  is 
dissolved  (no  reduction  will  take  place  in  the  cold). 

Now  add  50  cc.  of  50  per  cent,  sulphuric  acid  (by  vol- 
161 


SOAP-MAKING    MANUAL 

ume)  and  immerse  the  vessel  in  boiling  water  for  two 
hours  and  keep  protected  from  dust  and  organic  vapors, 
such  as  alcohol,  till  the  titration  is  completed.  Add  from 
a  weighing  bottle  a  slight  excess  of  the  ferrous  ammonium 
sulphate  (C),  making  spot  tests  on  a  porcelain  plate  with 
the  potassium  ferricyanide  (F).  Titrate  back  with  the 
dilute  bichromate.  From  the  amount  of  bichromate  re- 
duced calculate  the  percentage  of  glycerol. 

1  gram  glycerol  =  7.4564  grams  bichromate. 

1  gram  bichromate  =  0.13411  gram  glycerol. 

The  percentage  of  glycerol  obtained  above  includes  any 
oxidizable  impurities  present  after  the  purification.  A  cor- 
rection for  the  non-volatile  impurities  may  be  made  by 
running  a  bichromate  test  on  the  residue  at  160°  C. 

NOTES. 

(1)  It  is  important  that  the  concentration  of  acid  in 
the  oxidation  mixture  and  the  time  of  oxidation  should 
be  strictly  adhered  to. 

(2)  Before   the   bichromate   is  % added   to   the   glycerine 
solution  it  is  essential  that  the  slight  excess  of  lead  be  pre- 
cipitated  with   sulphuric   acid,   as   stipulated. 

(3)  For    crudes    practically    free    from    chlorides    the 
quantity  of  silver  carbonate  may  be  reduced  to   one-fifth 
and  the  basic  lead  acetate  to  0.5  cc. 

(4)  It  is  sometimes  advisable  to  add  a  little  potassium 
sulphate  to  insure  a  clear  nitrate. 

SAMPLING    CRUDE    GLYCERINE. 

The  usual  method  of  sampling  crude  glycerine  hitherto 
has  been  by  means  of  a  glass  tube,  which  is  slowly  lowered 
into  the  drum  with  the  object  of  taking  as  nearly  as  pos- 
sible a  vertical  section  of  the  glycerine  contained  in  the 

1C2 


ANALYTICAL  METHODS 

drum.  This  method  has  been  found  unsatisfactory,  owing 
to  the  fact  that  in  cold  climates  glycerine  runs  into  the 
tube  very  slowly,  so  that,  owing  to  the  time  occupied,  it  is 
impossible  to  take  a  complete  section  of  the  crude.  An- 
other objection  to  the  glass  tube  is  that  it  fails  to  take 
anything  approaching  a  correct  proportion  of  any  settled 
salt  contained  in  the  drum. 

The  sampler  which  is  illustrated  herewith  has  been  de- 
vised with  the  object  of  overcoming  the  objections  to  the 
glass  tube  as  far  as  possible.  It  consists  of  two  brass  tubes, 
one  fitting  closely  inside  the  other.  A  number  of  ports 
are  cut  out  in  each  tube  in  such  a  way  that  when  the  ports 
are  opened  a  continuous  slot  is  formed  which  enables  a 
complete  section  to  be  taken  throughout  the  entire  length 
of  the  drum.  By  this  arrangement  the  glycerine  fills  into 
the  sampler  almost  instantaneously.  There  are  a  number 
of  ports  cut  at  the  bottom  of  the  sampler  which  render  it 
possible  to  take  a  proportion  of  the  salt  at  the  bottom  of 
the  drum.  The  instrument  is  so  constructed  that  all  the 
ports,  including  the  bottom  ones,  can  be  closed  simulta- 
neously by  the  simple  action  of  turning  the  handle  at  the 
top ;  a  pointer  is  arranged  which  indicates  on  a  dial  when 
the  sampler  is  open  or  closed.  In  samplers  of  larger 
section  (1  in.)  it  is  possible  to  arrange  a  third  motion 
whereby  the  bottom  ports  only  are  open  for  emptying,  but 
in  samplers  of  smaller  dimensions  (fy&  in.)  this  third  mo- 
tion must  be  dispensed  with,  otherwise  the  dimensions  of 
the  ports  have  to  be  so  small  that  the  sampler  would  not 
be  efficient. 

In  using  the  sampler  it  is  introduced  into  the  drum  with 
the  ports  closed,  and  when  it  has  touched  the  bottom,  the 
ports  are  opened  for  a  second  or  two,  then  closed  and  with- 
drawn, and  the  sample  discharged  into  the  receiving  vessel 
by  opening  the  ports.  When  the  drum  contains  salt  which 

163 


SOAP-MAKING    MANUAL 

has  deposited,  the  ports  must  be  opened  before  the  sampler 
is  pushed  through  the  salt,  thus  enabling  a  portion  to  be  in- 
cluded in  the  sample.  It  is,  however,  almost  impossible  to 
obtain  a  correct  proportion  of  salt  after  it  has  settled  in 
the  drum  and  it  is  therefore  recommended  that  the  drum 
be  sampled  before  any  salt  has  deposited.  A  sampler  1  in. 
in  diameter  withdraws  approximately  10  oz.  from  a  110- 
gal.  drum.  A  sampler  fy&  in.  in  diameter  will  withdraw 
about  5  oz. 


164 


CHAPTER  VII 

Standard  Methods  for  the  Sampling  and  Analysis  of 
Commercial  Fats  and   Oils1 

The  following  report  of  the  Committee  on  Analysis  of 
Commercial  Fats  and  Oils  of  the  Division  of  Industrial 
Chemists  and  Chemical  Engineers  of  the  American  Chemi- 
cal Society  was  adopted  April  14,  1919,  by  unanimous  vote : 

W.   D.   RICHARDSON,   Chairman,  J.   R.   POWELL, 

Swift  and  Co.,   Chicago,  111.  Armour      Soap     Works,      Chi- 

R.  W.   BAILEY,  cage,    111. 

Stillwell    and    Gladding,    New  R.   J.    QUINN,* 

York  City.  Midland    Chemical    Co.,    Argo. 

W.  J.  GASCOYNE,  111. 

W.  J.  Gascoyne  and  Co.,  Bal-  PAUL    RUDNICK, 

timore,    Md.  Armour  and  Co.,  Chicago,  111. 

I.    KATZ,*  L.    M.   TOLMAN, 

Wilson   and   Co.,   Chicago,   111.  Wilson   and  Co.,   Chicago,   111. 

A.     LOWENSTEIN,*  E.     TWITCHELL,* 

Morris   and    Co.,    Chicago,    111.  Emery     Candle     Co.,     Cincin- 

H.  J.  MORRISON,  nati,    Ohio. 

Proctor      and      Gamble      Co.,  J.   J.   VOLLERTSEN, 

Ivorydale,  Ohio.  Morris   and    Co.,    Chicago,    111. 
'Resigned. 

Scope,  Applicability  and  Limitations  of  the  Methods. 

SCOPE. 

These  methods  are  intended  to  aid  in  determining  the 
commercial  valuation  of  fats  and  fatty  oils  in  their  purchase 
and  sale,  based  on  the  fundamental  assumption  commonly 
recognized  in  the  trade,  namely,  that  the  product  is  true  to 
name  and  is  not  adulterated.  For  methods  for  determining 
the  identity  of  oils  and  fats,  the  absence  of  adulterants  there- 
in and  for  specific  tests  used  in  particular  industries,  the 
chemist  is  referred  to  standard  works  on  the  analysis  of  fats 
and  oils. 

1  Approved  by  the  Supervisory  Committee  on  Standard  Methods  of 
Analysis  of  the  American  Chemical  Society. 

165 


SOAP-MAKING    MANUAL 

APPLICABILITY. 

The  methods  are  applicable  in  commercial  transactions 
involving  fats  and  fatty  oils  used  in  the  soap,  candle  and 
tanning  industries,  to  edible  fats  and  oils  and  to  fats  and 
fatty  oils  intended  for  lubricating  and  burning  purposes. 
The  methods  are  applicable  to  the  raw  oils  used  in  the 
varnish  and  paint  industry  with  the  exceptions  noted  under 
limitations,  but  special  methods  have  not  been  included. 

LIMITATIONS. 

The  methods  have  not  been  developed  with  special  refer- 
ence to  waxes  (beeswax,  carnauba  wax,  wool  wax,  etc.) 
although  some  of  them  may  be  found  applicable  to  these 
substances.  The  Committee  considers  the  Wijs  method 
superior  to  the  Hanus  method  for  the  determination  of 
iodine  number  of  linseed  oil  as  well  as  other  oils,  although 
the  Hanus  method  has  been  considered  standard  for  this 
work  for  "some  time  and  has  been  adopted  by  the  American 
Society  for  Testing  Materials  and  in  various  specifications. 
It  has  been  customary  to  use  the  Hiibl  method  for  the 
determination  of  iodine  value  of  tung  oil  (China  wood  oil) 
but  the  Committee's  work  indicates  that  the  Wijs  method 
is  satisfactory  for  this  determination. 

Sampling. 

TANK   CARS. 

1.  SAMPLING  WHILE  LOADING — Sample  shall  be  taken  at 
discharge  of  pipe  where  it  enters  tank  car  dome.  The  total 
sample  taken  shall  be  not  less  than  50  Ibs.  and  shall  be  a 
composite  of  small  samples  of  about  1  pound  each,  taken 
at  regular  intervals  during  the  entire  period  of  loading. 

The  sample  thus  obtained  is  thoroughly  mixed  and  uni- 
form 3-lb.  portions  placed  in  air-tight  3-lb.  metal  containers. 
At  least  three  such  samples  shall  be  put  up,  one  for  the 
buyer,  one  for  the  seller,  and  the  third  to  be  sent  to  a 

166 


STANDARD     METHODS 

referee  chemist  in  case  of  dispute.  All  samples  are  to  be 
promptly  and  correctly  labeled  and  sealed. 

2.  SAMPLING  FROM  CAR  ON  TRACK2 — (a)  When  contents 
are  solid.3  In  this  case  the  sample  is  taken  by  means  of 
a  large  tryer  measuring  about  2  in.  across  and  about  \l/2 
times  the  depth  of  the  car  in  length.  Several  tryerfuls  are 
taken  vertically  and  obliquely  toward  the  ends  of  the  car 
until  50  Ibs.  are  accumulated,  when  the  sample  is  softened, 
mixed  and  handled  as  under  (1).  In  case  the  contents  of 
the  tank  car  have  assumed  a  very  hard  condition,  as  in 
Winter  weather,  so  that  it  is  impossible  to  insert  the  tryer, 
and  it  becomes  necessary  to  soften  the  contents  of  the  car  by 
means  of  the  closed  steam  coil  (in  nearly  all  tank  cars  the 
closed  steam  coil  leaks)  or  by  means  of  open  steam  in  order 
to  draw  a  proper  sample,  suitable  arrangements  must  be 
made  between  buyer  tnd  seller  for  the  sampling  of  the 
car  after  it  is  sufficiently  softened,  due  consideration  being 
given  to  the  possible  presence  of  water  in  the  material  in 
the  car  as  received  and  also  to  the  possible  addition  of 
water  during  the  steaming.  The  Committee  knows  of  no 
direct  method  for  sampling  a  hard-frozen  tank  car  of  tallow 
in  a  satisfactory  manner. 

(&)  When  contents  are  liquid.  The  sample  taken  is  to 
be  a  50-lb.  composite  made  up  of  numerous  small  samples 
taken  from  the  top,  bottom  and  intermediate  points  by 
means  of  a  bottle  or  metal  container  with  removable  stopper 
or  top.  This  device  attached  to  a  suitable  pole  is  lowered 
to  the  various  desired  depths,  when  the  stopper  or  top  is 
removed  and  the  container  allowed  to  fill.  The  50-lb.  sample 
thus  obtained  is  handled  as  under  (1). 

2  Live   steam   must  not   be   turned   into   tank   cars   or   coils   before 
samples   are    drawn,    since   there   is   no   certain    way   of   telling   when 
coils  are  free  from  leaks. 

3  If  there  is  water  present  under   the   solid  material  this  must   be 
noted  and  estimated  separately. 

167 


SOAP-MAKING    MANUAL 

In  place  of  the  device  described  above,  any  sampler  capable 
of  taking  a  sample  from  the  top,  bottom,  and  center,  or 
from  a  section  through  car,  may  be  used. 

(c)  When  contents  are  in  semi-solid  condition,  or  when 
stearine  has  separated  from  liquid  portions.  In  this  case,  a 
combination  of  (a)  and  (b)  may  be  used  or  by  agreement 
of  the  parties  the  whole  may  be  melted  and  procedure  (&) 
followed. 

BARRELS,   TIERCES,   CASKS,   DRUMS,   AND  OTHER   PACKAGES. 

All  packages  shall  be  sampled,  unless  by  special  agreement 
the  parties  arrange  to  sample  a  lesser  number;  but  in  any 
case  not  less  than  10  per  cent  of  the  total  number  shall  be 
sampled.     The  total  sample  taken  shall  be  at  least  20  Ibs. 
in  weight  for  each  100  barrels,  or  equivalent. 

1.  BARRELS,  TIERCES  AND  CASKS — (a)  When  contents  are 
solid.  The  small  samples  shall  be  taken  by  a  tryer  through 
the  bunghole  or  through  a  special  hole  bored  in  the  head  or 
side  for  the  purpose,  with  a  1-in.  or  larger  auger.  Care 
should  be  taken  to  avoid  and  eliminate  all  borings  and  chips 
from  the  sample.  The  tryer  is  inserted  in  such  a  way  as  to 
reach  the  head  of  the  barrel,  tierce,  or  cask.  The  large 
sample  is  softened,  mixed  and  handled  according  to  TANK 

CARS    (1). 

(fe)  When  contents  are  liquid.  In  this  case  use  is  made 
of  a  glass  tube  with  constricted  lower  end.  This  is  in- 
serted slowly  and  allowed  to  fill  with  the  liquid,  when  the 
upper  end  is  closed  and  the  tube  withdrawn,  the  contents 
being  allowed  to  drain  into  the  sample  container.  After 
the  entire  sample  is  taken  it  is  thoroughly  mixed  and 
handled  according  to  TANK  CARS  (1). 

(c)  When  contents  are  semi-solid.  In  this  case  the  tryer 
or  a  glass  tube  with  larger  outlet  is  used,  depending  on  the 
degree  of  fluidity. 


STANDARD     METHODS 

(rf)  Very  hard  materials,  such  as  natural  and  artificial 
stearines.  By  preference  the  barrels  are  stripped  and 
samples  obtained  by  breaking  up  contents  of  at  least  10  per 
cent  of  the  packages.  This  procedure  is  to  be  followed 
also  in  the  case  of  cakes  shipped  in  sacks.  When  shipped 
in  the  form  of  small  pieces  in  sacks  they  can  be  sampled  by 
grab  sampling  and  quartering.  In  all  cases  the  final  pro- 
cedure is  as  outlined  under  TANK  CARS  (1). 

2.  DRUMS — Samples  are  to  be  taken  as  under    (1),  use 
being  made  of  the  bunghole.     The  tryer  or  tube  should  be 
sufficiently  long  to  reach  to  the  ends  of  the  drum. 

3.  OTHER  PACKAGES — Tubs,  pails  and  other  small  pack- 
ages not  mentioned  above  are  to  be  sampled  by  tryer  or  tube 
(depending  on  fluidity)  as  outlined  above,  the  tryer  or  tube 
being  inserted  diagonally  whenever  possible. 

4.  MIXED  LOTS  AND  PACKAGES — When  lots  of  tallow  or 
other  fats  are  received  in  packages  of  various  shapes  and 
sizes,  and  especially  wherein    the    fat  itself  is  of  variable 
composition,    such   must   be   left   to   the   judgment   of  the 
sampler.    If  variable,  the  contents  of  each  package  should 
be  mixed  as  thoroughly  as  possible  and  the  amount  of  the 
individual  samples  taken  made  proportional  to  the  sizes  of 
the  packages. 

Analysis. 

SAMPLE. 

The  sample  must  be  representative  and  at  least  three 
pounds  in  weight  and  taken  in  accordance  with  the  STAND- 
ARD METHODS  FOR  THE  SAMPLING  OF  COMMERCIAL  FATS  AND 

OILS.     It  must  be  kept  in  an  air-tight  container,  in  a  dark, 
cool  place. 

Soften  the  sample  if  necessary  by  means  of  a  gentle  heat, 
taking  care  not  to  melt  it.  When  sufficiently  softened,  mix 
the  sample  thoroughly  by  means  of  a  mechanical  egg  beater 
or  other  equally  effective  mechanical  mixer. 

169 


SOAP-MAKING     MANUAL 

MOISTURE    AND    VOLATILE    MATTER. 

APPARATUS:  Vacuum  Oven — The  Committee  Standard 
Oven. 

DESCRIPTION— The  Standard  F.  A.  C.  Vacuum  Oven  has 
been  designed  with  the  idea  of  affording  a  simple  and  com- 
pact vacuum  oven  which  will  give  as  uniform  temperatures 
as  possible  on  the  shelf.  As  the  figure  shows,  it  consists  of 
an  iron  casting  of  rectangular  sections  with  hinged  front 
door  made  tight  by  means  of  a  gasket  and  which  can  be 
lowered  on  opening  the  oven  so  as  to  form  a  shelf  on  which 
samples  may  be  rested.  The  oven  contains  but  one  shelf 
which  is  heated  from  above  as  well  as  below  by  means  of 
resistance  coils.  Several  thermometer  holes  are  provided  in 
order  to  ascertain  definitely  the  temperature  at  different 
points  on  the  shelf.  In  a  vacuum  oven  where  the  heating 
is  done  almost  entirely  by  radiation  it  is  difficult  to  maintain 
uniform  temperatures  at  all  points,  but  the  F.  A.  C.  oven 
accomplishes  this  rather  better  than  most  vacuum  ovens. 
Larger  ovens  containing  more  than  one  shelf  have  been 
tried  by  the  Committee,  but  have  been  found  to  be  lacking 
in  temperature  uniformity  and  means  of  control.  The  entire 
oven  is  supported  by  means  of  a  4-in.  standard  pipe  which 
screws  into  the  base  of  the  oven  and  which  in  turn  is  sup- 
ported by  being  screwed  into  a  blind  flange  of  suitable  di- 
ameter which  rests  on  the  floor  or  work  table. 

Moisture  Dish — A  shallow,  glass  dish,  lipped,  beaker 
form,  approximately  6  to  7  cm.  diameter  and  4  cm.  deep, 
shall  be  standard. 

DETERMINATION — Weigh  out  5  grams  (=0.2  g.  of  the 
prepared  sample  into  a  moisture  dish.  Dry  to  constant 
weight  in  vacua  at  a  uniform  temperature,  not  less  than  15° 
C.  nor  more  than  20°  C.  above  the  boiling  point  of  water  at 
the  working  pressure,  which  must  not  exceed  100  mm.  of 
mercury.4  Constant  weight  is  attained  when  successive 

170 


STANDARD     METHODS 


STANDARD  VACUUM  OVEN 


171 


SOAP-MAKING    MANUAL 

dryings  for  1-hr,  periods  show  an  additional  loss  of  not 
more  that  0.05  per  cent.  Report  loss  in  weight  as  MOIS- 
TURE AND  VOLATILE  MATTER.5 

The  vacuum-oven  method  cannot  be  considered  accurate 
in  the  case  of  fats  of  the  coconut  oil  group  containing  free 
acid  and  the  Committee  recommends  that  it  be  used  only  for 
oils  of  this  group  when  they  contain  less  than  1  per  cent 
free  acid.  In  the  case  of  oils  of  this  group  containing  more 
than  1  per  cent  free  acid,  recourse  should  be  had  tempor- 
arily to  the  routine  control  method  for  moisture  and  vola- 
tile matter6  until  the  Committee  develops  a  more  satisfactory 
method. 

The  air-oven  method  cannot  be  considered  even  approxi- 
mately accurate  in  the  case  of  the  drying  and  semi-drying 
oils  and  those  of  the  coconut  oil  group.  Therefore,  in  the 
case  of  such  oils  as  cottonseed  oil,  maize  oil  (corn  oil),  soy 
bean  oil,  linseed  oil,  coconut  oil,  palm  kernel  oil,  etc.,  the 
vacuum-oven  method  should  always  be  used,  except  in  the 
case  of  fats  of  the  coconut  group  containing  more  than  1 
per  cent  free  acid,  as  noted  above. 

INSOLUBLE    IMPURITIES. 

Dissolve  the  residue  from  the  moisture  and  volatile  matter 

4  Boiling  point  of  water  at  reduced  pressures. 

Pressure  Boiling  Point      Boiling  Point     Boiling  Point 

Mm.  Hg.  to  1°  C.  +  15°  C.  +  20°  C. 

100  52°   C.  67°  C.  72°  C. 

90  50  65  70 

80  47  62  67 

70  45  60  65 

60  42  57  62 

50  38  53  58  ' 

40  34  49  54 

5  Results  comparable  to  those  of  the  Standard  Method  may  be  ob- 
tained  on  most   fats  and  oils  by  drying  5-g.  portions  of  the  sample, 
prepared    and    weighed    as    above,    tc    constant   weight    in    a   well-con- 
structed   and   well-ventilated   air   oven   held   uniformly   at   a   tempera- 
ture of   105°   to  110°   C.     The  thermometer  bulb  should  be  close  to 
the  sample.     The  definition  of  constant  weight  is  the  same  as  for  the 
Standard  Method. 

172 


STANDARD     METHODS 

determination  by  heating  it  on  a  steam  bath  with  50  cc. 
of  kerosene.  Filter  the  solution  through  a  Gooch  crucible 
properly  prepared  with  asbestos,7  wash  the  insoluble  matter 
five  times  with  10-cc.  portions  of  hot  kerosene,  and  finally 
wash  the  residual  kerosene  out  thoroughly  with  petroleum 
ether.  Dry  the  crucible  and  contents  to  constant  weight,  as 
in  the  determination  of  moisture  and  volatile  matter  and 
report  results  as  INSOLUBLE  IMPURITIES. 

SOLUBLE    MINERAL   MATTER. 

Place  the  combined  kerosene  filtrate  and  kerosene  wash- 
ings from  the  insoluble  impurities  determination  in  a  plat- 
inum dish.  Place  in  this  an  ashless  filter  paper  folded  in  the 
form  of  a  cone,  apex  up.  Light  the  apex  of  the  cone,  where- 
upon the  bulk  of  the  kerosene  burns  quietly.  Ash  the  resi- 
due in  a  muffle,  to  constant  weight,  taking  care  that  the 
decomposition  of  alkaline  earth  carbonates  is  complete,  and 
report  the  result  as  SOLUBLE  MINERAL  MATTER.*  When  the 
percentage  of  soluble  mineral  matter  amounts  to  more  than 
0.1  per  cent,  multiply  the  percentage  by  10  and  add  this 
amount  to  the  percentage  of  free  fatty  acids  as  determined.9 

0  The  following  method  is  suggested  by  the  Committee  for  routine 
control  work:  Weigh  cut  5-  to  25-g.  portions  of  prepared  sample  into 
a  glass  or  aluminum  (Cauticn:  Aluminum  soap  may  be  formed) 
beaker  or  casserole  and  heat  on  a  heavy  asbestos  board  over  burner 
or  hot  plate,  taking  care  that  the  temperature  of  the  sample  does 
not  go  above  130°  C.  at  any  time.  During  the  heating  rotate  the 
vessel  gently  on  the  board  by  hand  to  avoid  sputtering  or  too  rapid 
evolution  cf  moisture.  The  proper  length  of  time  of  heating  is 
judged  by  absence  of  rising  bubbles  of  steam,  by  the  absence  of  foam 
or  by  other  signs  known  to  the  operator.  Avoid  overheating  of  sam- 
ple as  indicated  by  smoking  or  darkening.  Cool  in  desiccator  and 
weigh. 

Bv  co-operative  work  in  several  laboratrries,  the  Committee  has 
demonstrated  that  this  method  can  be  used  and  satisfactory  results 
obtained  on  coconut  oil  even  when  a  considerable  percentage  of  free 
fatty  acids  is  present,  and  the  method  is  recommended  for  this  pur- 
pose. Unfortunately  on  account  of  the  very  great  personal  factor 
involved,  the  Committee  cannot  establish  this  method  as  a  preferred 
method.  Nevertheless,  after  an  operator  has  learned  the  technique 
of  the  method,  it  gives  perfectly  satisfactory  results  for  ordinary 
oils  and  fats,  butter,  oleomargarine  and  coconut  oil,  and  deserves 
more  recognition  than  it  has  heretofore  received. 

173 


SOAP-MAKING    MANUAL 

FREE  FATTY  ACIDS. 

The  ALCOHOL10  used  shall  be  approximately  95  per  cent 
ethyl  alcohol,  freshly  distilled  from  sodium  hydroxide,  which 
with  phenolphthalein  gives  a  definite  and  distinct  end-point. 

DETERMINATION — Weigh  1  to  15  g.  of  the  prepared  sample 
into  an  Erlenmcyer  flask,  using  the  smaller  quantity  in  the 
case  of  dark-colored,  high  acid  fats.  Add  50  to  100  cc.  hot, 
neutral  alcohol,  and  titrate  with  N/2,  N/4  or  N/10  sodium 
hydroxide  depending  on  the  fatty  acid  content,  using  phenol- 
phthalein as  indicator.  Calculate  to  oleic  acid,  except  that  in 
the  case  of  palm  oil  the  results  may  also  be  expressed  in 
terms  of  palmitic  acid,  clearly  indicating  the  two  methods  of 
calculation  in  the  report.  In  the  case  of  coconut  and  palm 
kernel  oils,  calculate  to  and  report  in  terms  of  lauric  acid 
in  addition  to  oleic  acid,  clearly  indicating  the  two  methods 
of  calculation  in  the  report.  In  the  case  of  fats  or  greases 
containing  more  than  0.1  per  cent  of  soluble  mineral  matter, 
add  to  the  percentages  of  free  fatty  acids  as  determined 
10  times  the  percentage  of  bases  in  the  soluble  mineral 
matter  as  determined.9  This  addition  gives  the  equivalent 
of  fatty  acids  combined  with  the  soluble  mineral  matter. 


7  For    routine    control    work,    filter    paper    is    sometimes    more    con- 
venient  than    the   prepared   Gooch   crucible,    but    must   be  very   care- 
fully washed,  especially  around  the  rim,  to  remove  the  last  traces  of 
fat. 

8  For  routine  work,  an  ash  may  be  run  on  the  original  fat,  and  the 
soluble  mineral  matter  obtained  by  deducting  the  ash  en  the  insolu- 
ble  impurities  from  this.      In  this  case  the   Gooch   crucible   should  be 
prepared    with    an    ignited    asbestos    mat    so    that   the    impurities    may 
be  ashed  directly  after  being  weighed.     In  all  cases  ignition  should  be 
to   constant   weight   so    as   to   insure    complete    decomposition    of   car- 
bonates. 

9  See    note    on    Soluble    Mineral    Matter    following    these    methods. 
When   the  ash   contains  phosphates  the   factor    10   cannot   be  applied, 
but  the  bases  consisting  of  calcium  oxide,  etc.,  must  be  determined, 
and  the  factor   10  applied  to  them. 

10  For  routine  work  methyl  or  denatured  ethyl  alcohol  of  approxi- 
mately  95  per  cent  strength  may  be  used.     With  these  reagents  the 
end-point  is  not  sharp. 

174 


STANDARD     METHODS 

TITER. 

STANDARD  THERMOMETER — The  thermometer  is  graduated 
at  zero  and  in  tenth  degrees  from  10°  C  to  65°  C,  with  one 
auxiliary  reservoir  at  the  upper  end  and  another  between  the 
zero  mark  and  the  10°  mark.  The  cavity  in  the  capillary 
tube  between  the  zero  mark  and  the  10°  mark  is  at  least  1 
cm.  below  the  10°  mark,  the  10°  mark  is  about  3  or  4  cm. 
above  the  bulb,  the  length  of  the  thermometer  being  about 
37  cm.  over  all.  The  thermometer  has  been  annealed  for  75 
hrs.  at  450°  C.  and  the  bulb  is  of  Jena  normal  16'"  glass,  or 
its  equivalent,  moderately  thin,  so  that  the  thermometer  will 
be  quick-acting.  The  bulb  is  about  3  cm.  long  and  6  mm.  in 
diameter.  The  stem  of  the  thermometer  is  6  mm.  in  diam- 
eter and  made  of  the  best  thermometer  tubing,  with  scale 
etched  on  the  stem,  the  graduation  is  clear-cut  and  distinct, 
but  quite  fine.  The  thermometer  must  be  certified  by  the 
U.  S.  Bureau  of  Standards. 

GLVCEROL  CAUSTIC  SOLUTION — Dissolve  250  g.  potassium 
hydroxide  in  1900  cc.  dynamite  glycerin  with  the  aid  of 
heat. 

DETERMINATION — Heat  75  cc.  of  the  glycerol-caustic  solu- 
tion to  150°  C.  and  add  50  g.  of  the  melted  fat.  Stir  the 
mixture  well  and  continue  heating  until  the  melt  is  homo- 
geneous, at  no  time  allowing  the  temperature  to  exceed  150° 
C.  Allow  to  cool  somewhat  and  carefully  add  50  cc.  30 
per  cent  sulfuric  acid.  Now  add  hot  water  and  heat  until 
the  fatty  acids  separate  out  perfectly  clear.  Draw  off  the 
acid  water  and  wash  the  fatty  acids  with  hot  water  until  free 
from  mineral  acid,  then  filter  and  heat  to  130°  C.  as  rapidly 
as  possible  while  stirring.  Transfer  the  fatty  acids,  when 
cooled  somewhat,  to  a  1-in.  by  4-in.  titer  tube,  placed  in  a 
16-oz.  salt-mouth  bottle  of  clear  glass,  fitted  with  a  cork 
that  is  perforated  so  as  to  hold  the  tube  rigidly  when  in 
position.  Suspend  the  titer  thermometer  so  that  it  can  be 

175 


SOAP-MAKING    MANUAL 

used  as  a  stirrer  and  stir  the  fatty  acids  slowly  (about  100 
revolutions  per  minute)  until  the  mercury  remains  station- 
ary for  30  seconds.  Allow  the  thermometer  to  hang  quietly 
with  the  bulb  in  the  center  of  the  tube  and  report  the 
highest  point  to  which  the  mercury  rises  as  the  titer  of  the 
fatty  acids.  The  titer  should  be  made  at  about  20°  C.  for  all 
fats  having  a  titer  above  30°  C.  and  at  10°  C.  below  the 
titer  for  all  other  fats.  Any  convenient  means  may  be  used 
for  obtaining  a  temperature  of  10°  below  the  titer  of  the 
various  fats.  The  committee  recommends  first  of  all  a  chill 
room  for  this  purpose ;  second,  an  artificially  chilled  small 
chamber  with  glass  window ;  third,  immersion  of  the  salt- 
mouth  bottle  in  water  or  other  liquid  of  the  desired  tem- 
perature. 

UNSAPONIFIABLE   MATTER. 

EXTRACTION  CYLINDER — The  cylinder  shall  be  glass- 
stoppered,  graduated  at  40  cc.,  80  cc.  and  130  cc.,  and  of  the 
following  dimensions:  diameter  about  \y%  in.,  height  about 
12  in. 

PETROLEUM  ETHER — Redistilled  petroleum  ether,  boiling 
under  75°  C.,  shall  be  used.  A  blank  must  be  made  by 
evaporating  250  cc.  with  about  0.25  g.  of  stearine  or  other 
hard  fat  (previously  brought  to  constant  weight  by  heating) 
and  drying  as  in  the  actual  determination.  The  blank  must 
not  exceed  a  few  milligrams. 

DETERMINATION— Weigh  5  g.  (±0.20  g.)  of  the  prepared 
sample  into  a  200-cc.  Erlenmeyer  flask,  add  30  cc.  of  re- 
distilled 95  per  cent  (approximately)  ethyl  alcohol  and  5  cc. 
of  50  per  cent  aqueous  potassium  hydroxide,  and  boil  the 
mixture  for  one  hour  under  a  reflux  condenser.  Transfer 
to  the  extraction  cylinder  and  wash  to  the  40-cc.  mark  with 
redistilled  95  per  cent  ethyl  alcohol.  Complete  the  transfer, 
first  with  warm,  then  with  cold  water,  till  the  total  volume 
amounts  to  80  cc.  Cool  the  cylinder  and  contents  to  room 

176 


STANDARD     METHODS 

temperature  and  add  50  cc.  of  petroleum  ether.  Shake 
vigorously  for  one  minute  and  allow  to  settle  until  both 
layers  are  clear,  when  the  volume  of  the  upper  layer  should 
be  about  40  cc.  Draw  off  the  petroleum  ether  layer  as 
closely  as  possible  by  means  of  a  slender  glass  siphon  into  a 
separatory  funnel  of  500  cc.  capacity.  Repeat  extraction  at 
least  four  more  times,  using  50  cc.  of  petroleum  ether  each 
time.  More  extractions  than  five  are  necessary  where  the 
unsaponifiable  matter  runs  high,  say  over  5  per  cent,  and 
also  in  some  cases  where  it  is  lower  than  5  per  cent,  but 
is  extracted  with  difficulty.  Wash  the  combined  extracts  in 
a  separatory  funnel  three  times  with  25-cc.  portions  of  10 
per  cent  alcohol,  shaking  vigorously  each  time.  Transfer 
the  petroleum  ether  extract  to  a  wide-mouth  tared  flask  or 
beaker,  and  evaporate  the  petroleum  ether  on  a  steam  bath 
in  an  air  current.  Dry  as  in  the  method  for  MOISTURE  AND 
VOLATILE  MATTER.  Any  blank  must  be  deducted  from  the 
weight  before  calculating  unsaponifiable  matter.  Test  the 
final  residue  for  solubility  in  50  cc.  petroleum  ether  at  room 
temperature.  Filter  and  wash  free  from  the  insoluble  resi- 
due, if  any,  evaporate  and  dry  in  the  same  manner  as  be- 
fore. The  Committee  wishes  to  emphasize  the  necessity 
of  thorough  and  vigorous  shaking  in  order  to  secure 
accurate  results.  The  two  phases  must  be  brought  into  the 
most  intimate  contact  possible,  otherwise  low  and  disagree- 
ing results  may  be  obtained. 

IODINE  NUMBER — WIJS    METHOD. 

PREPARATION  OF  REAGENTS — Wijs  Iodine  Solution — Dis- 
solve 13.0  g.  of  resublimed  iodine  in  one  liter  of  C.  P.  glacial 
acetic  acid  and  pass  in  washed  and  dried  chlorine  gas  until 
the  original  thiosulfate  titration  of  the  solution  is  not  quite 
doubled.  The  solution  is  then  preserved  in  amber  glass- 
stoppered  bottles,  sealed  with  paraffin  until  ready  for  use. 

Mark  the  date  on  which  the  solution  is  prepared  on  the 
177 


SOAP-MAKING    MANUAL 

bottle  or  bottles  and  do  not  use  Wijs  solution  which  is  more 
than  30  days  old. 

There  should  be  no  more  than  a  slight  excess  of  iodine, 
and  no  excess  of  chlorine.  When  the  solution  is  made 
from  iodine  and  chlorine,  this  point  can  be  ascertained  by 
not  quite  doubling  the  titration.11 

The  glacial  acetic  acid  used  for  preparation  of  the  Wijs 
solution  should  be  of  99.0  to  99.5  per  cent  strength.  In 
case  of  glacial  acetic  acids  of  somewhat  lower  strength,  the 
Committee  recommends  freezing  and  centrifuging  or  drain- 
ing as  a  means  of  purification. 

JV/10  Sodium  Thiosulfate  Solution — Dissolve  24.8  g.  of 
C.  P.  sodium  thiosulfate  in  recently  boiled  distilled  water 
and  dilute  with  the  same  to  one  liter  at  the  temperature  at 
which  the  titrations  are  to  be  made. 

Starch  Paste— Boil  1  g.  of  starch  in  200  cc.  of  distilled 
water  for  10  min.  and  cool  to  room  temperature. 

An  improved  starch  solution  may  be  prepared  by  auto- 
claving  2  g.  of  starch  and  6  g.  of  boric  acid  dissolved  in  200 
cc.  water  at  15  Ibs.  pressure  for  15  min.  This  solution  has 
good  keeping  qualities. 

"P.  C.  Mcllhiney,  J.  Am.  Chcm.  Soc.,  29  (1917),  1222,  gives 
the  following  details  for  the  preparation  of  the  iodine  monochloride 
solution: 

The  preparation  of  the  iodine  moncchloride  solution  presents  no 
great  difficulty,  but  it  must  be  dene  with  care  and  accuracy  in  order 
to  obtain  satisfactory  results.  There  must  be  in  the  scluticn  no 
sensible  excess  either  of  iodine  or  more  particularly  of  chlorine,  over 
that  required  to  form  the  mcnochlcride.  This  condition  is  mcst  satis- 
factorily attained  by  dissolving  in  the  whole  of  the  acetic  acid  to  be 
used  the  requisite  quantity  of  iodine,  using  a  gentle  heat  to  assist 
the  solution,  if  it  is  found  necessary,  setting  aside  a  small  portion 
of  this  solution,  while  pure  and  dry  chlorine  is  passed  into  the  re- 
mainder until  the  halogen  content  of  the  whole  solution  is  doubled. 
Ordinarily  it  will  be  found  that  by  passing  the  chlorine  into  the 
main  part  of  the  solution  until  the  characteristic  color  of  free  iodine 
has  just  been  discharged  there  will  be  a  slight  excess  of  chlorine 
which  is  corrected  by  the  addition  of  the  requisite  amount  of  the 
unchlorinated  portion  until  all  free  chlorine  has  been  destroyed.  A 
slight  excess  of  iodine  does  little  or  no  harm,  but  excess  of  chlorine 
must  be  avoided. 

178 


STANDARD     METHODS 

Potassium  Iodide  Solution — Dissolve  150  g.  of  potassium 
iodide  in  water  and  make  up  to  one  liter. 

A/yiO  Potassium  Bichromate— Dissolve  4.903  g.  of  C.  P. 
potassium  bichromate  in  water  and  make  the  volume  up  to 
one  liter  at  the  temperature  at  which  titrations  are  to  be 
made. 

The  Committee  calls  attention  to  the  fact  that  occasionally 
potassium  bichromate  is  found  containing  sodium  bichro- 
mate, although  this  is  of  rare  occurrence.  If  the  analyst 
suspects  that  he  is  dealing  with  an  impure  potassium 
bichromate,  the  purity  can  be  ascertained  by  titration  against 
re-sublimed  iodine.  However,  this  is  unnecessary  in  the 
great  majority  of  cases. 

Standardisation  of  the  Sodium  Thiosulfate  Solution — 
Place  40  cc.  of  the  potassium  bichromate  solution,  to  which 
has  been  added  10  cc.  of  the  solution  of  potassium  iodide, 
in  a  glass-stoppered  flask.  Add  to  this  5  cc.  of  strong 
hydro-chloric  acid.  Dilute  with  100  cc.  of  water,  and  allow  the 
A*/ 10  sodium  thiosulfate  to  flow  slowly  into  the  flask  until 
the  yellow  color  of  the  Iquid  has  almost  disappeared.  Add 
a  few  drops  of  the  starch  paste,  and  with  constant  shaking 
continue  to  add  the  Ar/10  sodium  thiosulfate  solution  until 
the  blue  color  just  disappears. 

DETERMINATION — Weigh  accurately  from  0.10  to  0.50  g. 
(depending  on  the  iodine  number)  of  the  melted  and  filtered 
sample  into  a  clean,  dry,  16-oz.  glass-stoppered  bottle  con- 
taining 15-20  cc.  of  carbon  tetrachloride  or  chloroform.  Add 
25  cc.  of  iodine  solution  from  a  pipette,  allowing  to  drain 
for  a  definite  time.  The  excess  of  iodine  should  be  from 
50  per  cent  to  60  per  cent  of  the  amount  added,  that  is, 
from  100  per  cent  to  150  per  cent  of  the  amount  absorbed. 
Moisten  the  stopper  with  a  15  per  cent  potassium  iodide  so- 
lution to  prevent  loss  of  iodine  or  chlorine  but  guard  against 
an  amount  sufficient  to  run  down  inside  the  bottle.  Let 

179 


SOAP-MAKING    MANUAL 

the  -bottle  stand  in  a  dark  place  for  J^  hr.  at  a  uniform 
temperature.  At  the  end  of  that  time  add  20  cc.  of  15  per 
cent  potassium  iodide  solution  and  100  cc.  of  distilled  water. 
Titrate  the  iodine  with  TV/10  'sodium  thiosulfate  solution 
which  is  added  gradually,  with  constant  shaking,  until  the 
yellow  color  of  the  solution  has  almost  disappeared.  Add 
a  few  drops  of  starch  paste  and  continue  titration  until  the 
blue  color  has  entirely  disappeared.  Toward  the  end  of  the 
reaction  stopper  the  bottle  and  shake  violently  so  that  any 
iodine  remaining  in  solution  in  the  tetrachloride  or  chloro- 
form may  be  taken  up  by  the  potassium  iodide  solution. 
Conduct  two  determinations  on  blanks  which  must  be  run 
in  the  same  manner  as  the  sample  except  that  no  fat  is  used 
in  the  blanks.  Slight  variations  in  temperature  quite  appre- 
ciably affect  the  titer  of  the  iodine  solution,  as  acetic  acid 
has  a  high  coefficient  of  expansion.  It  is,  therefore,  essen- 
tial that  the  blanks  and  determinations  on  the  sample  be 
made  at  the  same  time.  The  number  of  cc.  of  standard 
thiosulfate  solution  required  by  the  blank,  less  the  amount 
used  in  the  determination,  gives  the  thiosulfate  equivalent 
of  the  iodine  absorbed  by  the  amount  of  sample  used  in  the 
determination.  Calculate  to  centigrams  of  iodine  absorbed 
by  1  g.  of  sample  (=  per  cent  iodine  absorbed). 

DETERMINATION,  TUNG  OIL — Tung  oil  shows  an  erratic 
behavior  with  most  iodine  reagents  and  this  is  particularly 
noticeable  in  the  case  of  the  Hanus  reagent  which  is  entirely 
unsuitable  for  determining  the  iodine  number  of  this  oil 
since  extremely  high  and  irregular  results  are  obtained. 
The  Hiibl  solution  shows  a  progressive  absorption  up  to  24 
hrs.  and  probably  for  a  longer  time  but  the  period  required 
is  entirely  too  long  for  a  chemical  determination.  The  Wijs 
solution  gives  good  results  if  the  following  precautions  are 
observed : 

Weigh  out  0.15  ±  0.05  g.,  use  an  excess  of  55  ±  3  per 

180 


STANDARD     METHODS 

cent  Wijs  solution.  Conduct  the  absorption  at  a  temperature 
of  20-25°  C.  for  1  hr.  In  other  respects  follow  the  instruc- 
tions detailed  above. 

SAPONIFICATION    NUMBER     (KOETTSTORFER    NUMBER). 

PREPARATION  OF  REAGENTS.  N/2  Hydrochloric  Acid — 
Carefully  standardized. 

Alcoholic  Potassium  Hydroxide  Solution — Dissolve  40  g. 
of  pure  potassium  hydroxide  in  one  liter  of  95  per  cent  re- 
distilled alcohol  (by  volume).  The  alcohol  should  be  re- 
distilled from  potassium  hydroxide  over  which  it  has  been 
standing  for  some  time,  or  with  which  it  has  been  boiled  for 
some  time,  using  a  reflux  condenser.  The  solution  must  be 
clear  and  the  potassium  hydroxide  free  from  carbonates. 

DETERMINATION — Weigh  accurate  about  5  g.  of  the  filtered 
sample  into  a  250  to  300  cc.  Erlenmeyer  flask.  Pipette  5& 
cc.  of  the  alcoholic  potassium  hydroxide  solution  into  the 
flask,  allowing  the  pipette  to  drain  for  a  definite  time.  Con- 
nect the  flask  with  an  air  condenser  and  boil  until  the  fat 
is  completely  saponified  (about  30  minutes).  Cool  and 
titrate  with  the  N/2  hydrochloric  acid,  using  phenolphthalein 
as  an  indicator.  Calculate  the  Koettstorfer  number  (mg. 
of  potassium  hydroxide  required  to  saponify  1  g.  of  fat). 
Conduct  2  or  3  blank  determinations,  using  the  same  pipette 
and  draining  for  the  same  length  of  time  as  above. 

MELTING   POINT. 

APPARATUS — Capillary  tubes  made  from  5  mm.  inside  di- 
ameter thin-walled  glass  tubing  drawn  out  to  1  mm.  inside 
diameter.  Length  of  capillary  part  of  tubes  to  be  about 
5  cm.  Length  of  tube  over  all  8  cm. 

Standard  thermometer  graduated  in  tenths  of  a  degree. 

600  cc.  beaker. 

DETERMINATION — The  sample  should  be  clear  when  melted 

181 


SOAP-MAKING    MANUAL 

and  entirely  free  from  moisture,  or  incorrect  results  will  be 
obtained. 

Melt  and  thoroughly  mix  the  sample.  Dip  three  of  the 
capillary  tubes  above  described  in  the  oil  so  that  the  fat  in 
the  tube  stands  about  1  cm.  in  height.  Now  fuse  the  capil- 
lary end  carefully  by  means  of  a  small  blast  flame  and 
allow  to  cool.  These  tubes  are  placed  in  a  refrigerator  over 
night  at  a  temperature  of  from  40  to  50°  F.  They  are  then 
fastened  by  means  of  a  rubber  band  or  other  suitable  means 
to  the  bulb  of  a  thermometer  graduated  in  tenths  of  a  de- 
gree. The  thermometer  is  suspended  in  a  beaker  of  water 
(which  is  agitated  by  air  or  other  suitable  means)  so  that 
the  bottom  of  the  bulb  of  the  thermometer  is  immersed  to 
a  depth  of  about  3  cm.  The  temperature  of  the  water  is 
increased  gradually  at  the  rate  of  about  1°  per  minute. 

The  point  at  which  the  sample  becomes  opalescent  is  first 
noted  and  the  heating  continued  until  the  contents  of  the 
tube  becomes  uniformly  transparent.  The  latter  tempera- 
ture is  reported  as  the  melting  point. 

Before  finally  melting  to  a  perfectly  clear  fluid,  the  sample 
becomes  opalescent  and  usually  appears  clear  at  the  top, 
bottom,  and  sides  before  becoming  clear  at  the  center.  The 
heating  is  continued  until  the  contents  of  the  tube  become 
uniformly  clear  and  transparent.  This  temperature  is  re- 
ported as  the  melting  point.12  It  is  usually  only  a  fraction 
of  a  degree  above  the  opalescent  point  noted.  The  ther- 
mometer should  be  read  to  the  nearest  l/2°  C.,  and  in  addi- 
tion this  temperature  may  be  reported  to  the  nearest  degree 
Fahrenheit  if  desired. 

CLOUD  TEST. 

PRECAUTIONS — (1)  The  oil  must  be  perfectly  dry,  because 


12  The  melting  point  of  oils  may  be  determined  in  general  according 
to  the  above  procedure,  taking  into  consideration  the  lower  tempera- 
ture required. 

182 


STANDARD     METHODS 

the  presence  of  moisture  will  produce  a  turbidity  before  the 
clouding  point  is  reached. 

(2)  The  oil  must  be  heated  to  150°  C.  over  a  free  flame, 
immediately  before  making  the  test. 

(3)  There  must  not  be  too  much  discrepancy  between  the 
temperature  of  the  bath  and  the  clouding  point  of  the  oil. 
An  oil  that  will  cloud  at  the  temperature  of  hydrant  water 
should  be  tested  in  a  bath  of  that  temperature.    An  oil  that 
will  cloud  in  a  mixture  of  ice  and  water  should  be  tested  in 
such  a  bath.    An  oil  that  will  not  cloud  in  a  bath  of  ice 
and  water  must  be  tested  in  a  bath  ef  salt,  ice,  and  water. 

DETERMINATION — The  oil  is  heated  in  a  porcelain  casserole 
over  a  free  flame  to  150°  C,  stirring  with  the  thermometer. 
As  soon  as  it  can  be  done  with  safety,  the  oil  is  transferred 
to  a  4  oz.  oil  bottle,  which  must  be  perfectly  dry.  One  and 
one-half  ounces  of  the  oil  are  sufficient  for  the  test.  A  dry 
centigrade  thermometer  is  placed  in  the  oil,  and  the  bottle 
is  then  cooled  by  immersion  in  a  suitable  bath.  The  oil  is 
constantly  stirred  with  the  thermometer,  taking  care  not  to 
remove  the  thermometer  from  the  oil  at  any  time  during 
the  test,  so  as  to  avoid  stirring  air  bubbles  into  the  oil. 
The  bottle  is  frequently  removed  from  the  bath  for  a  few 
moments.  The  oil  must  not  be  allowed  to  chill  on  the 
sides  and  bottom  of  the  bottle.  This  is  effected  by  constant 
and  vigorous  stirring  with  the  thermometer.  As  soon  as 
the  first  permanent  cloud  shows  in  the  body  of  the  oil,  the 
temperature  at  which  this  cloud  occurs  is  noted. 

With  care,  results  concordant  to  within  l/2°  C.  can  be  ob- 
tained by  this  method.  A  Fahrenheit  thermometer  is  some- 
times used  because  it  has  become  customary  to  report  re- 
sults in  degrees  Fahrenheit. 

The  oil  must  be  tested  within  a  short  time  after  heating 
to  150°  C.  and  a  re-test  must  always  be  preceded  by  re- 
heating to  that  temperature.  The  cloud  point  should  be 

183 


SOAP-MAKING    MANUAL 

approached  as  quickly  as  possible,  yet  not  so  fast  that  the 
oil  is  frozen  on  the  sides  or  bottom  of  the  bottle  before  the 
cloud  test  is  reached. 

Notes  on  the  Above  Methods. 

SAMPLING. 

The  standard  size  of  sample  adopted  by  the  committee  is 
at  least  3  Ibs.  in  weight.  The  committee  realizes  that  this 
amount  is  larger  than  any  samples  usually  furnished  even 
when  representing  shipments  of  from  20,000  to  60,000  Ibs. 
but  it  believes  that  the  requirement  of  a  larger  sample  is 
desirable  and  will  work  toward  uniform  and  more  con- 
cordant results  in  analysis.  It  will  probably  continue  to  be 
the  custom  of  the  trade  to  submit  smaller  buyers'  samples 
than  required  by  the  committee,  but  these  are  to  be  consid- 
ered only  as  samples  for  inspection  and  not  for  analysis.  The 
standard  analytical  sample  must  consist  of  3  Ibs.  or  more. 

The  reasons  for  keeping  samples  in  a  dark,  cool  place  are 
obvious.  This  is  to  prevent  any  increase  in  rancidity  and 
any  undue  increase  in  free  fatty  acids.  In  the  case  of  many 
fats  the  committee  has  found  in  its  co-operative  analytical 
work  that  free  acid  tends  to  increase  very  rapidly.  This 
tendency  is  minimized  by  low  temperatures. 

MOISTURE  AND  VOLATILE  MATTER. 

After  careful  consideration  the  committee  has  decided  that 
moisture  is  best  determined  in  a  vacuum  oven  of  the  design 
which  accompanies  the  above  report.  Numerous  results  on 
check  samples  have  confirmed  the  committee's  conclusions. 
The  oven  recommended  by  the  committee  is  constructed  on 
the  basis  of  well-known  principles  and  it  is  hoped  that  this 
type  will  be  adopted  generally  by  chemists  who  are  called 
upon  to  analyze  fats  and  oils.  The  experiments  of  the  com- 
mittee indicate  that  it  is  a  most  difficult  matter  to  design  a 
vacuum  oven  which  will  produce  uniform  temperatures 

184 


STANDARD     METHODS 

throughout;  and  one  of  the  principal  ideas  in  the  design 
adopted  is  uniformity  of  temperature  over  the  entire  single 
shelf.  This  idea  has  not  quite  been  realized  in  practice  but, 
nevertheless,  the  present  design  approaches  much  closer  to 
the  ideal  than  other  vacuum  ovens  commonly  used.  In  the 
drawing  the  essential  dimensions  are  those  between  the  heat- 
ing units  and  the  shelf  and  the  length  and  breadth  of  the 
outer  casting.  The  standard  Fat  Analysis  Committee  Oven 
(F.  A.  C.  Oven)  can  be  furnished  by  Messrs.  E.  H.  Sargent 
&  Company,  125  West  Lake  street,  Chicago. 

The  committee  realizes  that  for  routine  work  a  quicker 
method  is  desirable  and  has  added  one  such  method  and 
has  also  stated  the  conditions  under  which  comparable  re- 
sults can  be  obtained  by  means  of  the  ordinary  well-venti- 
iated  air  oven  held  at  105  to  110°  C.  However,  in  accord- 
ance with  a  fundamental  principle  adopted  by  the  committee 
at  its  first  meeting,  only  one  standard  method  is  adopted  and 
declared  official  for  each  determination. 

The  committee  realizes  that  in  the  case  of  all  methods 
for  determining  moisture  by  means  of  loss  on  heating  there 
may  be  a  loss  due  to  volatile  matter  (especially  fatty  acids) 
other  than  water.  The  title  of  the  determination  MOISTURE 
AND  VOLATILE  MATTER  indicates  this  idea,  but  any  considerable 
error  from  this  source  may  occur  only  in  the  case  of  high 
acid  fats  and  oils  and  particularly  those  containing  lower 
fatty  acids  such  as  coconut  and  palm  kernel  oil.  In  the 
case  of  extracted  greases  which  have  not  been  properly  puri- 
fied, some  of  the  solvent  may  also  be  included  in  the  mois- 
ture and  volatile  matter  determination,  but  inasmuch  as  the 
solvent,  usually  a  petroleum  product,  can  only  be  considered 
as  foreign  matter,  for  commercial  purposes,  it  is  entirely 
proper  to  include  it  with  the  moisture. 

The  committee  has  also  considered  the  various  distillation 
methods  for  the  determination  of  moisture  in  fats  and  oils, 

185 


SOAP-MAKING    MANUAL 

but  since  according  to  the  fundamental  principles  which  it 
was  endeavoring  to  follow  it  could  only  standardize  one 
method,  it  was  decided  that  the  most  desirable  one  on  the 
whole  was  the  vacuum-oven  method  as  given.  There  are 
cases  wherein  a  chemist  may  find  it  desirable  to  check  a 
moisture  determination  or  investigate  the  moisture  content 
of  a  fat  or  oil  further  by  means  of  one  of  the  distillation 
methods. 

However,  in  co-operative  work  the  distillation  method  in 
various  types  of  apparatus  has  not  yielded  satisfactory  re- 
sults. The  difficulties  appear  to  be  connected  with  a  proper 
choice  of  solvent  and  particularly  with  the  tendency  of 
drops  of  water  to  adhere  to  various  parts  of  the  glass  ap- 
paratus instead  of  passing  on  to  the  measuring  device. 
When  working  on  coconut  oil  containing  a  high  percentage 
of  free  fatty  acids,  concordant  results  could  not  be  obtained 
by  the  various  members  of  the  committee  when  working 
with  identical  samples,  solvents  and  apparatus. 

On  the  other  hand,  the  committee  found  by  individual 
work,  co-operative  work  and  collaborative  work  by  several 
members  of  the  committee  in  one  laboratory,  that  the  old, 
well-known  direct  heating  method  (which  the  committee  has 
designated  the  hot  plate  method)  yielded  very  satisfactory 
results  on  all  sorts  of  fats  and  oils  including  emulsions  such 
as  butter  and  oleomargarine  and  even  on  coconut  oil  sam- 
ples containing  15  to  20  per  cent  free  fatty  acids  and  5  to  6 
per  cent  of  moisture.  Unfortunately,  this  method  depends 
altogether  on  the  operator's  skill  and  while  the  method  may 
be  taught  to  any  person  whether  a  chemist  or  not  so  that 
he  can  obtain  excellent  results  with  it,  it  is  difficult  to  give 
a  sufficiently,  complete  description  of  it  so  that  any  chemist 
anywhere  after  reading  the  description  could  follow  it  suc- 
cessfully. The  method  is  undoubtedly  worthy  of  much  con- 
fidence in  careful  hands.  It  is  quick,  accurate  and  reliable. 

186 


STANDARD     METHODS 

It  is  probably  the  best  single  method  for  the  determination 
of  moisture  in  all  sorts  of  samples  for  routine  laboratory 
work.  On  account  of  this  fact  the  committee  desires  to 
announce  its  willingness  to  instruct  any  person  in  the  proper 
use  of  the  method  who  desires  to  become  acquainted  with  it 
and  who  will  visit  any  committee  member's  laboratory. 

INSOLUBLE  IMPURITIES. 

This  determination,  the  title  for  which  was  adopted  after 
careful  consideration,  determines  the  impurities  which  have 
generally  been  known  as  dirt,  suspended  matter,  suspended 
solids,  foreign  solids,  foreign  matter,  etc.,  in  the  past.  The 
first  solvent  recommended  by  the  committee  is  hot  kerosene 
to  be  followed  by  petroleum  ether  kept  at  ordinary  room 
temperature.  Petroleum  ether,  cold  or  only  slightly  warm, 
is  not  a  good  fat  and  metallic  soap  solvent,  whereas  hot 
kerosene  dissolves  these  substances  readily,  and  for  this 
reason  the  committee  has  recommended  the  double  solvent 
method  so  as  to  exclude  metallic  soaps  which  are  determined 
below  as  soluble  mineral  matter. 

SOLUBLE    MINERAL   MATTER. 

Soluble  mineral  matter  represents  mineral  matter  com- 
bined with  fatty  acids  in  the  form  of  soaps  in  solution  in 
the  fat  or  oil.  Formerly,  this  mineral  matter  was  often  de- 
termined in  combination  by  weighing  the  separated  metallic 
soap  or  by  weighing  it  in  conjunction  with  the  insoluble  im- 
purities. Since  the  soaps  present  consist  mostly  of  lime 
soap,  it  has  been  customary  to  calculate  the  lime  present 
therein  by  taking  0.1  the  weight  of  the  total  metallic  soaps. 
The  standard  method  as  given  above  is  direct  and  involves 
no  calculation.  The  routine  method  given  in  the  note  has 
been  placed  among  the  methods  for  the  reason  that  it  is 
used  in  some  laboratories,  but  has  not  been  adopted  as  a 
standard  method  in  view  of  the  fact  that  the  committee  has 

187 


SOAP-MAKING    MANUAL 

made  it  a  rule  to  adopt  only  one  standard  method.  It 
should  be  pointed  out,  however,  that  the  method  cannot  be 
considered  accurate  for  the  reason  that  insoluble  impurities 
may  vary  from  sample  to  sample  to  a  considerable  extent 
and  the  error  due  to  the  presence  of  large  particles  of  in- 
soluble impurities  is  thus  transferred  to  the  soluble  mineral 
matter.  The  committee  has  found  one  type  of  grease 
(naphtha  bone  grease)  which  shows  most  unusual  charac- 
teristics. The  type  sample  contains  4.3  per  cent  soluble 
mineral  matter  by  the  committee  -method  which  would  be 
equivalent  to  43.0  per  cent  free  fatty  acid.  The  kerosene 
and  gasoline  nitrate  was  particularly  clear,  nevertheless  the 
ash  was  found  to  contain  36.43  per  cent  P2O8  equivalent  to 
79.60  per  cent  of  CaaCPO*);,  and  9.63  per  cent  of  Fe2O3. 
The  method,  therefore,  determines  the  soluble  mineral  mat- 
ter in  this  case  satisfactorily  but  the  factor  10  is  not  ap- 
plicable for  calculating  the  fatty  acids  combined  therewith. 
It  is  necessary,  therefore,  in  order  to  determine  the  fatty 
acids  combined  with  soluble  mineral  matter  in  the  original 
sample  to  determine  the  actual  bases  in  the  soluble  mineral 
matter  as  obtained  by  ashing  the  kerosene  and  gasoline  fil- 
trate. To  the  bases  so  determined  the  factor  10  can  then 
be  applied. 

FREE  FATTY  ACID. 

The  fatty  acid  method  adopted  is  sufficiently  accurate  for 
commercial  purposes.  In  many  routine  laboratories  the  fat 
or  oil  is  measured  and  not  weighed,  but  the  committee  rec- 
ommends weighing  the  sample  in  all  cases.  For  scientific 
purposes  the  result  is  often  expressed  as  "acid  number," 
meaning  the  number  of  milligrams  of  KOH  required  to 
neutralize  the  free  acids  in  one  gram  of  fat,  but  the  com- 
mercial practice  has  been,  and  is,  to  express  the  fatty  acids 
as  oleic  acid  or  in  the  case  of  palm  oil,  as  palmitic  acid, 
in  some  instances.  The  'committee  sees  no  objection  to  the 


STANDARD     METHODS 

continuation  of  this  custom  so  long  as  the  analytical  report 
clearly  indicates  how  the  free  acid  is  expressed.  For  a 
more  exact  expression  of  the  free  acid  in  a  given  fat,  the 
committee  recommends  that  the  ratio  of  acid  number  to 
saponification  number  be  used.  This  method  of  expressing 
results  is  subject  to  error  when  unsaponifiable  fatty  matter 
is  present,  since  the  result  expresses  the  ratio  of  free  fatty 
acid  to  total  saponifiable  fatty  matter  present. 

TITER. 

At  the  present  time  the  prices  of  gycerol  and  caustic  pot- 
ash are  abnormally  high,  but  the  committee  has  considered 
that  the  methods  adopted  are  for  normal  times  and  normal 
prices.  For  routine  work  during  the  period  of  high  prices 
the  following  method  may  be  used  for  preparing  the  fatty 
acids  and  is  recommended  by  the  committee: 

Fifty  grams  of  fat  are  saponified  with  60  cc.  of  a  solution 
of  2  parts  of  methyl  alcohol  to  1  of  50  per  cent  NaOH. 
The  soap  is  dried,  pulverized  and  dissolved  in  1000  cc.  of 
water  in  a  porcelain  dish  and  then  decomposed  with  25  cc. 
of  75  per  cent  sulphuric  acid.  The  fatty  acids  -are  boiled 
until  clear  oil  is  formed  and  then  collected  and  settled  in  a 
150-cc.  beaker  and  filtered  into  a  50-cc.  beaker.  They  are 
then  heated  to  130°  C.  as  rapidly  as  possible  with  stirring, 
and  transferred,  after  they  have  cooled  somewhat,  to  the 
usual  1-in.  by  4-in.  titer  tube. 

The  method  of  taking  the  titer,  including  handling  the 
thermometer,  to  be  followed  is  the  same  as  that  described  in 
the  standard  method.  Even  at  present  high  prices  many 
laboratories  are  using  the  glycerol-caustic  potash  method 
for  preparing  the  fatty  acids,  figuring  that  the  saving  of 
time  more  than  compensates  for  the  extra  cost  of  the  re- 
agents. Caustic  soda  cannot  'be  substituted  for  caustic  pot- 
ash in  the  glycerol  method. 

189 


SOAP-MAKING    MANUAL 

UNSAPONIFIABLE    MATTER. 

The  committee  has  considered  unsaponifiable  matter  to 
include  those  substances  frequently  found  dissolved  in  fats 
and  oils  which  are  not  saponified  by  the  caustic  alkalies  and 
which  at  the  same  time  are  soluble  in  the  ordinary  fat 
solvents.  The  term  includes  such  substances  as  the  higher 
alcohols,  such  as  cholesterol  which  in  found  in  animal  fats, 
phytosterol  found  in  some  vegetable  fats,  paraffin  and  petro- 
leum oils,  etc.  UNSAPONIFIABLE  MATTER  should  not  be  con- 
fused in  the  lay  mind  with  INSOLUBLE  IMPURITIES  OR  SOLUBLE 

MINERAL   MATTER. 

The  method  adopted  by  the  committee  has  been  selected 
only  after  the  most  careful  consideration  of  other  methods, 
such  as  the  dry  extraction  method  and  the  wet  method  mak- 
ing use  of  the  separatory  funnel.  At  first  consideration  the 
dry  extraction  process  would  seem  to  offer  the  best  basis 
for  an  unsaponifiable  matter  method,  but  in  practice  it  has 
been  found  absolutely  impossible*  for  different  analysts  to 
obtain  agreeing  results  when  using  any  of  the  dry  extrac- 
tion methods  proposed.  Therefore,  this  method  had  to  be 
abondoned  after  numerous  trials,  although  several  members 
of  the  committee  strongly  favored  it  in  the  beginning. 

IODINE  NUMBER — The  iodine  number  adopted  by  the  com- 
mittee is  that  determined  by  the  well-known  Wijs  method. 
This  method  was  adopted  after  careful  comparison  with  the 
Hanus  and  Hiibl  methods.  The  Hiibl  method  was  elimi- 
nated from  consideration  almost  at  the  beginning  of  the  com- 
mittee's work  for  the  reason  that  the  time  required  for 
complete  absorption  of  the  iodine  is  unnecessarily  long  and, 
in  fact,  even  after  absorption  has  gone  on  over  night,  it  is 
apparently  not  complete.  In  the  case  of  the  Hanus  and  Wijs 
methods  complete  absorption  takes  place  in  from  15  minutes 
to  an  hour,  depending  on  conditions.  Formerly,  many 
chemists  thought  the  Hanus  solution  rather  easier  to  prepare 

190 


STANDARD     METHODS 

than  the  Wijs  solution,  but  the  experience  of  the  committee 
was  that  the  Wijs  solution  was  no  more  difficult  to  prepare 
than  the  Hanus.  Furthermore,  absorption  of  iodine  from 
the  Wijs  solution  appeared  to  take  place  with  greater 
promptness  and  certainty  than  from  the  Hanus  and  was 
complete  in  a  shorter  time.  Results  by  the  Wijs  method 
were  also  in  better  agreement  in  the  case  of  oils  showing 
high  iodine  absorption  than  with  the  Hanus  solution  and 
showed  a  slightly  higher  iodine  absorption  for  the  same 
length  of  time.  However,  the  difference  was  not  great. 
The  committee  investigated  the  question  of  substitution 
since  it  has  been  suggested  that  in  case  of  the  Wijs  solution 
substitution  of  iodine  in  the  organic  molecule  might  occur, 
and  found  no  evidence  of  this  in  the  time  required  for 
the  determination,  namely,  y*  hr.,  or  even  for  a  somewhat 
longer  period.  One  member  of  the  committee  felt  that  it 
was  not  desirable  to  introduce  the  Wijs  method  into  these 
standard  methods  since  the  Hanus  method  was  already 
standardized  by  the  Association  of  Official  Agricultural 
Chemists,  but  the  committee  felt  that  it  must  follow  the 
principle  established  at  the  commencement  of  its  work, 
namely,  that  of  adopting  the  method  which  appeared  to 
be  the  best  from  all  standpoints,  taking  into  consideration 
accuracy,  convenience,  simplicity,  time,  expense,  etc.,  with- 
out allowing  precedent  to  have  the  deciding  vote. 

IODINE  NUMBER,  TUNG  OIL — The  committee  has  made  an 
extensive  study  of  the  application  of  the  Wijs  method  to 
the  determination  of  iodine  value  in  the  case  of  tung  oil 
with  the  result  that  it  recommends  the  method  for  this  oil 
but  has  thought  it  desirable  to  limit  the  conditions  under 
which  the  determination  is  conducted  rather  narrowly,  al- 
though reasonably  good  results  are  obtained  by  the  com- 
mittee method  without  making  use  of  the  special  limitations. 

The  co-operative  work  of  the  committee  and  the  special 
191 


SOAP-MAKING    MANUAL 

investigations  conducted  by  individual  members  bring  out 
the  following  points : 

Influence  of  Temperature— From  16°  C.  to  30°  C.  there 
is  a  moderate  increase  in  the  absorption,  but  above  30°  the 
increase  is  rather  rapid  so  that  it  was  thought  best  to 
limit  the  temperature  in  the  case  of  tung  oil  to  20°  to  25°  C. 

Influence  of  Time — The  absorption  increases  with  the 
time  but  apparently  complete  absorption,  so  far  as  unsat- 
urated  bonds  are  concerned,  occurs  well  within  one  hour's 
time.  Consequently,  one  hour  was  set  as  the  practical  limit. 

Influence  of  Excess — The  excess  of  iodine  solution  also 
tends  to  increase  the  iodine  number,  hence  the  Committee 
thought  it  necessary  to  limit  the  excess  rather  rigidly  to 
55  ±  3  per  cent,  although  with  greater  latitude  results  were 
reasonably  good. 

Influence  of  Age  of  Solution — Old  solutions  tend  to  give 
low  results  although  up  to  2  mo.  no  great  differences  were 
observed.  Nevertheless,  it  was  thought  best  to  limit  the  age 
of  the  solution  to  30  days — long  enough  for  all  practical 
purposes. 

Amount  of  Sample — As  a  practical  amount  of  sample  to 
'be  weighed  out  the  Committee  decided  on  0.15  g.  with  a 
tolerance  of  0.05  g.  in  either  direction  according  to  prefer- 
ence. In  other  words,  the  amount  of  sample  to  be  taken 
for  the  determination  to  be  from  0.1  to  0.2  g.  in  the  discre- 
tion of  the  analyst. 

The  Committee's  study  of  the  Hiibl  method  which  has 
been  adopted  by  the  Society  for  Testing  Materials  in  the 
case  of  tung  oil  indicates  that  this  method  when  applied 
to  tung  oil  is  subject  to  the  same  influences  as  the  Wijs 
method  and  it  has  the  additional  very  serious  disadvantage 
of  requiring  a  long  period  of  time  for  absorption  which 
cannot  be  considered  reasonable  for  a  modern  analytical 
method.  When  using  the  Htibl  solution,  the  absorption  is 

192 


STANDARD    METHODS 

not  complete  in  the  case  of  tung  oil  at  3,  7,  18  or  even  24 
lirs. 

The  Hanus  method  in  the  case  of  tung  oil  gives  very 
high  and  erratic  results,  as  high  as  180  to  240  in  ordinary 
cases  for  an  oil  whose  true  iodine  number  is  about  165. 

MELTING  POINT. 

A  melting  point  is  the  temperature  at  which  a  solid  sub- 
stance assumes  the  liquid  condition.  If  the  solid  is  a  pure 
substance  in  the  crystalline  condition  the  melting  point  is 
sharp  and  well  defined  for  any  given  pressure.  With  in- 
creased pressure  the  melting  point  is  lowered  or  raised,  de- 
pending on  whether  the  substance  contracts  or  expands  in 
melting.  The  lowering  or  raising  of  the  melting  point  with 
pressure  is  very  slight  and  ordinarily  is  not  taken  into 
consideration.  Melting-point  determinations  are  commonly 
carried  out  under  ordinary  atmospheric  pressures  without 
correction.  The  general  Effect  of  soluble  impurities  is  to 
lower  the  melting  point,  and  this  holds  true  whether  the 
impurity  has  a  higher  or  lower  melting  point  than  the  pure 
substance  (solvent).  Thus  if  a  small  amount  of  stearic  acid 
be  added  to  liquid  palmitic  acid  and  the  solution  frozen,  the 
melting  point  of  this  solid  will  be  lower  than  that  of  palmitic 
acid.  Likewise  the  melting  point  of  stearic  acid  is  lowered 
by  the  addition  of  a  small  amount  of  palmitic  acid.  A  eutec- 
tic  mixture  results  when  two  components  solidify  simulta- 
neously at  a  definite  temperature.  Such  a  mixture  has  a 
constant  melting  point  and  because  of  this  and  also  because 
both  solid  and  liquid  phases  have  the  same  composition, 
eutectic  mixtures  were  formerly  looked  upon  as  com- 
pounds. The  phenomenon  of  double  melting  points  has 
been  observed  in  the  case  of  a  number  of  glycerides.  Such 
a  glyceride  when  placed  in  the  usual  capillary  tube  and 
subjected  to  increasing  temperature  quickly  resolidifies  only 

193 


SOAP-MAKING    MANUAL 

to  melt  again  and  remain  melted  at  a  still  higher  tempera- 
ture. This  phenomenon  has  not  yet  been  sufficiently  in- 
vestigated to  afford  a  satisfactory  explanation. 

Non-crystalline  substances  such  as  glass,  sealing  wax  and 
various  other  waxes  and  wax  mixtures,  and  most  colloidal 
substances  do  not  exhibit  a  sharp  melting  point,  but  under 
the  application  of  heat  first  soften  very  gradually  and  at  a 
considerably  higher  temperature  melt  sufficiently  to  flow. 
This  phenomenon  of  melting  through  a  long  range  of  tem- 
perature may  be  due  to  the  amorphous  nature  of  the  sub- 
stance or  to  the  fact  that  it  consists  of  a  very  large  number 
of  components  of  many  different  melting  points. 

The  fats  and  oils  of  natural  origin,  that  is,  the  animal  and 
vegetable  fats  and  oils,  consist  of  mixtures  of  glycerides  and, 
generally  speaking,  of  a  considerable  number  of  such  com- 
ponents. These  components  are  crystalline  and  when  sep- 
arated in  the  pure  state  have  definite  melting  points,  al- 
though some  exhibit  the  phenomenon  of  double  melting 
point.  For  the  most  part  the  naturally  occurring  glycerides 
are  mixed  glycerides.  In  the  natural  fats  and  oils  there  are 
present  also  certain  higher  alcohols,  of  which  cholesterol  is 
characteristic  of  the  animal  fats  and  oils  and  phytosterol  of 
many  of  the  vegetable  fats  and  oils.  In  addition  to  the 
crystalline  glycerides  and  the  higher  alcohols  present  in 
neutral  fats,  there  are  in  fats  of  lower  grade,  fatty  acids, 
which  are  crystalline,  and  also  various  non-crystalline  im- 
purities of  an  unsaponifiabe  nature,  and  the  presence  of 
these  impurities  tends  to  lower  the  melting  point.  They 
also  tend  to  induce  undercooling  and  when  the  liquid  fat  or 
oil  is  being  chilled  for  purposes  of  solidification  or  in  de- 
termination of  titer. 

The  presence  of  water,  especially  when  this  is  thoroughly 
mixed  or  emulsified  with  a  fat  or  oil,  also  influences  the 
melting  point  to  a  marked  extent,  causing  the  mixture  to 

194 


STANDARD     METHODS 

melt  through  a  longer  range  of  temperatures  than  would  be 
the  case  if  the  water  were  absent.  This  is  particularly  true 
of  emulsified  fats  and  oils,  such  as  butter  and  oleomargarine, 
both  of  which  contain,  besides  water,  the  solids  naturally 
present  in  milk  or  cream  and  including  casein,  milk  sugar, 
and  salts.  The  melting-point  method  recommended  by  the 
Committee  is  not  applicable  to  such  emulsions  or  other 
watery  mixtures  and  the  Committee  has  found  it  impossible 
to  devise  an  accurate  method  for  making  softening-point  or 
melting-point  determinations  on  products  of  this  nature. 
Not  only  the  amount  of  water  present  but  also  the  fineness 
of  its  particles,  that  is,  its  state  of  subdivision  and  distri- 
bution, in  a  fat  or  oil  influences  the  softening  point  or  melt- 
ing point  and  causes  it  to  vary  widely  in  different  samples. 

As  a  consequence  of  the  foregoing  facts,  natural  fats  and 
oils  do  not  exhibit  a  definite  melting  point,  composed  as  they 
are  of  mixtures  of  various  crystalline  glycerides,  higher 
alcohols,  fatty  acids,  and  non-cystalline  substances.  There- 
fore, the  term  melting  point  when  applied  to  them  requires 
further  definition.  They  exhibit  first  a  lower  melting  point 
(the  melting  point  of  the  lowest  melting  component)  or 
what  might  be  called  the  softening  point  and  following  this 
the  fat  softens  through  a  shorter  or  longer  range  of  tem- 
perature to  the  final  melting  point  at  which  temperature  the 
fat  is  entirely  liquid.  This  is  the  melting  point  determined 
by  the  Committee's  melting-point  method.  The  range  be- 
tween the  softening  point  and  the  final  melting  point  varies 
greatly  with  the  different  fats  and  oils  depending  on  their 
chemical  components,  the  water  associated  with  them, 
emulsification,  etc.  In  the  case  of  coconut  oil  the  range 
between  softening  point  and  final  melting  point  is  rather 
short;  in  the  case  of  butter,  long.  Various  methods  have 
been  devised  to  determine  the  so-called  melting  point  of  fats 
and  oils.  Most  of  these  methods,  however,  determine,  not 

195 


SOAP-MAKING    MANUAL 

the  melting  point,  but  the  softening  point  or  the  flow  point 
of  the  fat  and  the  great  difficulty  has  been  in  the  past  to 
devise  a  method  which  would  determine  even  this  point 
with  reasonable  accuracy  and  so  that  results  could  be  easily 
duplicated.  It  has  been  the  aim  of  the  Committee  to 
devise  a  simple  method  for  the  determination  of  the  melting 
point  of  fats  and  oils,  but  it  should  be  understood  that  the 
term  melting  point  in  the  scientific  sense  is  not  applicable  to 
natural  fats  and  oils. 


196 


PLANT  AND 
MACHINERY 

Illustrations  of  machinery  and  layouts 

of  the  plant  of  a  modern  soap-making 

establishment. 


197 


PLANT    AND    MACHINERY 


HOIST,  LYE  TANK,  ETC. 


MELTING-OUT  TROUGH 
199 


SOAP-MAKING    MANUAL 


200 


PLANT    AND    MACHINERY 


201 


CRUTCHER  (CROSS  SECTION) 


HORIZONTAL  CRUTCHER 


CRUTCHER 


202 


PLANT    AND    MACHINERY 


WRAPPING  MACHINE 
(LAUNDRY  SOAP) 


SLABBER 


CUTTING  TABLE 
203 


SOAP-MAKING    MANUAL 


AUTOMATIC  POWER  CUTTING  TABLE 


AUTOMATIC  PRESS   (LAUNDRY) 

204 


PLANT    AND    MACHINERY 


CUTTING  TABLE   (HAND) 


CARTON   WRAPPING   MACHINE 

205 


SOAP-MAKING    MANUAL 


DRYING  RACKS 


SOAP  POWDER  Box 


PLANT    AND    MACHINERY 


SOAP-MAKING    MANUAL 


FLUFFY  SOAP  POWDER  EQUIPMENT 


208 


PLANT    AND    MACHINERY 


SOAP  POWDER   MIXER 


SOAP  POWDER  MILL 


209 


SOAP-MAKING    MANUAL 


210 


PLANT    AND    MACHINERY 


211 


SOAP-MAKING    MANUAL 


TOILET  SOAP  MILL 


TOILET  SOAP  MILL 
212 


PLANT    AND    MACHINERY 


CHIPPER 


PLODDER 


HORIZONTAL  CHIPPER 


AMALGAMATOR  (IMPROVED) 


213 


SOAP-MAKING    MANUAL 


PRESS    (LETTERING   ON       PRESS    (FOOT)  PRESS    (FOOT) 

4  SIDES  OF  CAKE) 


PLANT    AND    MACHINERY 


AUTOMATIC  PRESS    (TOILET) 


MULTIPLE  CAKE  CUTTER 


CAKE  CUTTER 


CHIPPER 


215 


SOAP-MAKING    MANUAL 


216 


PLANT    AND    MACHINERY 


217 


SOAP-MAKING     MANUAL 


218 


Appendix 


Tables   marked   *   are  taken  from  the  German  Year 
Book  for  Soap  Industry. 

219 


SOAP-MAKING    MANUAL 

(U.  S.  BUREAU  OF  STANDARDS) 
THE  METRIC  SYSTEM. 

The  fundamental  unit  of  the  metric  system  is  the  meter 
(the  unit  of  length).  From  this  the  units  of  mass 
(gram)  and  capacity  (liter)  are  derived.  All  other  units 
are  the  decimal  sub-divisions  or  multiples  of  these.  These 
three  units  are  simply  related,  so  that  for  all  practical 
purposes  the  volume  of  one  kilogram  of  water  (one  liter) 
is  equal  to  one  cubic  decimeter. 


Prefixes.               Meaning. 

Units. 

Milli-  =  one  thousandth  1-1000      .001 
Centi-  =  one  hundredth  1-100        .01 
Deci-  =  one  tenth  1-10                   .1 
Unit  =  one                                      1. 
Deka-  =  ten  10-1                         10. 
Hecto-  —  one  hundred  100-1    100. 
Kilo-  =  one  thousand  1000-1  1000. 

Meter   for   length. 
Gram  for  mass. 
Liter  for  capacity. 

The  metric  terms  are  formed  by  combining  the  words 
"Meter,"  "Gram"  and  "Liter"  with  the  six  numerical 
prefixes. 

LENGTH 

10  milli-meters    m m  =  1  centi-meter    cm 

10  centi-meters    =  1  deci-meter   dm 

10  deci-meters    =  1  meter    (about  40  inches) m 

10  meters   =  1  deka-meter   dkm 

10  deka-meters    =  1  hecto-meter  h  m 

10  hecto-meters =  1  kilo-meter  (about  M  mile),  .km 

220 


APPENDIX 
MASS. 

10  milli-grams .   m  g  =  1  centi-gram   eg 

10  centi-grams  =  1  deci-gram    d  g 

10  deci-grams =  1  gram  (about  15  grains) g 

10  grams   =1  deka-gram    dkg 

10  Deka-grams  =  1  hecto-gram   hg 

10  hecto-grams   =  1  kilo-gram  (about  2  pounds). kg 


CAPACITY. 

10  milli-liters   ...ml  =  1  centi-liter   c  1 

10  centi-liters    =  1  deci-liter    d  1 

10  deci-liters    =  1  liter  (about  1  quart) 1 

10  liters   =1  deka-liter  d  k  1 

10  deka-liters    =  1  hecto-liter  (about  a  barrel) ..hi 

10  hecto-liters    =1  kilo-liter    k  1 

The  square  and  cubic  units  are  the  squares  and  cubes  of 
the  linear  units. 

The  ordinary  unit  of  land  area  is  the  Hectare   (about 
2y2  acres). 


221 


SOAP-MAKING    MANUAL 

U.  S.  BUREAU  OF  STANDARDS  TABLE  OF 
METRIC  EQUIVALENTS 


Meter  =  39.37  inches. 

Legal   Equivalent  Adopted  by  Act  of   Congress   July  28, 
1866. 


LENGTH. 

Centimeter =  0.3937  inch 

Meter =3.28  feet 

Meter =  1.094  yards 

Kilometer    =  0.621  statute  mile 

Kilometer    =  0.5396  nautical  mile 

Inch   =  2.540  centimeters 

Foot    =  0.305  meter 

Yard   =  0.914  meter 

Statute  mile =  1.61  kilometers 

Nautical  mile =  1.853  kilometers 

AREA. 

Sq.    centimeter =    0.155  sq.  inch 

Sq.  meter =  10.76  sq.  feet 

Sq.  meter =     1.196  sq.  yards 

Hectare  =    2.47  acres 

Sq.  kilometer —     0.386  sq.  mile 

Sq.    inch =    6.45  sq.   centimeters 

Sq.  foot =     0.0929  sq.  meter 

Sq.  yard =    0.836  sq.  meter 

Acre    =    0.405  hectare 

Sq.  mile =    2.59  sq.  kilometers 

222 


APPENDIX 
WEIGHT. 

Gram    =  15.43  grains 

Gram   =    0.772  U.  S.  apoth.  scruple 

Gram    =     0.2572  U.  S.  apoth.  dram 

Gram    =    0.0353  avoir,  ounce 

Gram   —    0.03215  troy  ounce 

Kilogram  =    2.205  avoir,  pounds 

Kilogram  =    2.679  troy  pounds 

Metric  ton =    0.984  gross  or  long  ton 

Metric  ton =    1.102  short  or  net  tons 

Grain =    0.064  gram 

U.  S.  apoth.  scruple =    1.296  grams 

U.  S.  apoth.  dram =  -  3.89  grams 

Avoir,  ounce =  28.35  grams 

Troy  ounce =  31.10  grams 

Avoir,  pound =    0.4536  kilogram 

Troy  pound =     0.373  kilogram 

Gross  or  long  ton =    1.016  metric  tons 

Short  or  net  ton =     0.907  metric  ton 

VOLUME. 

Cu.  centimeter =    0.0610  cu.  inch 

Cu.  meter =  35.3  cu.  feet 

Cu.  meter =    1.308  cu.  yards 

Cu.  inch =  16.39  cu.  centimeters 

Cu.  foot =    0.283  cu.  meter 

Cu.  yard =    0.765  cu.  meter 

223 


SOAP-MAKING    MANUAL 
CAPACITY. 

Millimeter   =    0.0338  U.  S.  liq.  ounce 

Millimeter  =    0.2705  U.  S.  apoth.  dram 

Liter   =     1.057    U.  S.  liq.  quarts 

Liter   =    0.2642  U.  S.  liq.  gallon 

Liter   =    0.908    U.  S.  dry  quart 

Dekaliter    =    1.135    U.  S.  pecks 

Hectoliter  =    2.838    U.  S.  bushels 

U.  S.  liq.  ounce =  29.57      millimeters 

U.  S.  apoth.  dram —    3.70      millimeters 

U.  S.  liq.  quarts =    0.946    liter 

U.  S.  dry  quarts =     1.101     liters 

U.  S.  liq.  gallon =    3.785    liters 

U.S.  peck =    0.881    dekaliter 

U.  S.  bushel..  .  =    0.3524  hectoliter 


AVOIRDUPOIS  WEIGHT. 

1  pound  =  16  ounces  =  256  drams 
1  ounce    =16       u 


TROY  (APOTHECARIES')  WEIGHT  (U.  S.) 

1  pound  =   12  ounces  =  96  drams  =  288  scruples  =  5,760  grains 

1  ounce     =     8  drams  =     24  scruples  =      480  grains 

1  dram     =       3  scruples  =        60  grains 

1  scruple     =        20  grains 


WINE  (APOTHECARIES)  LIQUID  MEASURE  (U.  S.) 

1  gallon  =  8  pints  =  128  fl.  ozs.  =  1,024  fl.  drams  =  61,440  minims 

1  pint    =     16  fl.  ozs.  =      128  fl.  drams  =     7,689  minims 

1  fl.  oz.    =          8  fl.  drams  =        480  minims 

1  fl.  dram    =          60  minims 

224 


Useful  Information 

To  find  diameter  of  a  circle  multiply  circumference  by 
.31831. 

To  find  circumference  of  a  circle,  multiply  diameter  by 
3.1416. 

To  find  area  of  a  circle,  multiply  square  of  diameter  by 
7854. 

To  find  surface  of  a  ball,  multiply  square  of  diameter  by 
3.1416. 

To  find  side  of  an  equal  square,  multiply  diameter  by 
.8862. 

To  find  cubic  inches  in  a  ball,  multiply  cube  of  diameter 
by  .5236. 

Doubling  the  diameter  of  a  pipe,  increases  its  capacity 
four  times. 

One  cubic  font  of  anthracite  coal  weighs  about  53  lb&. 

One  cubic  foot  of  bituminous  coal  weighs  from  47  to  50 
pounds. 

A  gallon  of  water  (U.  S.  standard)  weighs  8  1/3  pounds 
and  contains  231  cubic  inches. 

A  cubic  foot  of  water  contains  7l/2  gallons,  1728  cubic 
inches  and  weighs  62^  pounds. 

To  find  the  number  of  pounds  of  water  a  cylindrical 
tank  contains,  square  the  diameter,  multiply  by  .785  and 
then  by  the  height  in  feet.  This  gives  the  number  of  cubic 
feet  which  multiplied  by  62l/2  gives  the  capacity  in  pounds 
of  water.  Divide  by  7l/2  and  this  gives  the  capacity  in  gal- 
lons. 

A  horse-power  is  equivalent  to  raising  33,000  pounds  1 
foot  per  minute,  or  550  pounds  1  foot  per  second. 

225 


SOAP-MAKING    MANUAL 

The  friction  of  water  in  pipes  is  as  the  square  of  velocity. 
The  capacity  of  pipes  is  as  the  square  of  their  diameters ; 
thus,  doubling  the  diameter  of  a  pipe  increases  its  capacity 
four  times. 

To  find  the  diameter  of  a  pump  cylinder  to  move  a  given 
quantity  of  water  per  minute  (100  feet  of  piston  being  the 
standard  of  speed),  divide  the  number  of  gallons  by  4, 
then  extract  the  square  root,  and  the  product  will  be  the 
diameter  in  inches  of  the  pump  cylinder. 

To  find  the  horse-power  necessary  to  elevate  water  to  a 
given  height,  multiply  the  weight  of  the  water  elevated  per 
minute  in  pounds  by  the  height  in  feet,  and  divide  the 
product  by  33,000  (an  allowance  should  be  added  for  water 
friction,  and  a  further  allowance  for  loss  in  steam  cylinder, 
say  from  20  to  30  per  cent). 

To  compute  the  capacity  of  pumping  engines,  multiply 
the  area  of  water  piston,  in  inches,  by  the  distance  it  travels, 
in  inches,  in  a  given  time.  Deduct  3  per  cent  for  slip  and 
rod  displacement.  The  product  divided  by  231  gives  the 
number  of  gallons  in  time  named. 

To  find  the  velocity  in  feet  per  minute  necessary  to  dis- 
charge a  given  volume  of  water  in  a  given  time,  multiply 
the  number  of  cubic  feet  of  water  by  144  and  divide  the 
product  by  the  area  of  the  pipe  in  inches. 

To  find  the  area  of  a  required  pipe,  the  volume  and  vel- 
ocity of  water  being  given,  multiply  the  number  of  cubic 
feet  of  water  by  144  and  divide  the  product  by  the  velocity 
in  feet  per  minute.  The  area  being  found,  the  diameter  can 
be  learned  by  using  any  table  giving  the  "area  of  circles" 
and  finding  the  nearest  area,  opposite  to  which  will  be  found 
the  diameter  to  correspond. 

226 


USEFUL    INFORMATION 


Physical  and  Chemical  Constants  of  Fixed  Oils  and  Fats. 

(FROM  LEWKOWITSCH  AND  OTHER  AUTHORITIES.) 


Specific  gravity 
atlS'C. 

Specific 
£S& 

Meltine-polnt. 

Solidifylng-point 

.  0.931-0.938 
0.925-0.931 
0.925-0.926 
0.924-0.927 
0.924-0.926 
0.925-0.923 
0.921-0.926 
0.922-0.930 
0.923-0.924 
0.914-0.917 
0.916-0.920 
0.942-0.955 
0.960-0.966 
0.915-0.919 
0.915-0.920 
0.916-0.920 
0.914-0.917 
0.927-0.933 
0.922-0.927 
0.924-0.929 
0.920-0.930 
0.917-0.918 
0.926 
0.914-0.916 
0.919-0.923 
0.921-0.925 
0.950-0.952 
0.925-0.926 
0.905 
0.970-0.980 
0.931-0.938 
0.914-0.91G 
0.943-0.952 
0.927-0.936 
0.924-0.930 
0.875-0.884 
0.879-0.880 
0.990-0.999 
0.973 
0.958-0.969 
0.960 
0.970 
0.936-0.942 
0.924-0.927 

0.880 

-16°  to  —26° 

—16° 

—27° 
—27° 
—18° 
—17° 
—27°  to  —30° 
—10°  to  —15° 
12° 
—  5° 
—2°  to  -10' 
—  17.56 
—16° 
—  12°  to  —18" 
—14° 
—10°  to  —20° 
_3»  to  —7° 
2° 
—4° 
0°to—  10°  • 
3° 
—2° 
5°  to—  38 
—16° 
0°  to  1.5° 
31°  to  32.5° 

25°'  to  26° 
16°  to  20° 
39°  to  43° 
46° 
29° 
15°  to  17' 
35°  to  37° 
19°  to  20° 

Hemp-seed  oil  .... 
Walnut  oil 

0.871 
0.873 
0.919 

Sunflower  oil           .  . 
Fir-seed  oil    . 

Cotton-seed  oil         .   . 
Sesame  oil     . 
Rape-seed  oil           .   . 
Black  mustard  oil    .   . 

6.867" 
0.871 
0.863 

•  ' 



Castor  oil    
Apricot-kernel  oil    .   . 
Almond  oil    
Peanut  (arachis)  oil    . 
Olive  oil      

0.910 

0.867 
0.862 

0:874 
0.873 
0.872 

0.871 
0.861 
0.867 
0.856 
0.858 
0.873 
0.875 
0.875 
0.861 

0.860 
0.866 
0.859 
0.833 
0.827 
0.842 
0.901 
0.822 
0.812 
0.810 

Menhaden  oil    .... 
Cod-liver  oil  
Seal  oil    ... 



AVhaleoil   
Dolphin  oil    ,  .  .  .  . 
Porpoise  oil   
Neat's-foot  oil  .... 
Cotton-seed  stearine    . 
Palin  oil     

.    •'.'  .    .    . 

40° 
27°  to  42° 
30°  to  33° 
20°  to  26° 
40°  to  44° 
51°  to  54.5° 
41°  to  46° 
21°  to  22° 
42°  to  46° 
29.5°  to  33° 

Cacao  butter  .  ,  .  .  . 
Cocoa-nut  oil  
Myrtle  wax    
Japan  wax  ...... 
Lard        ....... 

Bone  fat  

Tallow     
Butter  fat       

Oleomargarine  .... 
Sperm  oil    ...... 
Bottle-nose  oil  .     .  .  . 
Carnauba  wax  .... 
Wool-fat  
Beeswax   

—25° 

80°  to'  81°  " 
30°  to  30.2° 
60.5°  to  62° 
43.4°  to  44.2° 
80.5°  to  81° 
below  -17° 
8°  to  15° 

84°'  to  85°  ' 
39°  to  42° 
62°  to  64° 
43.5°  to  49° 
80.5°  to  81° 

Spermaceti  
Chinese  wax   
Tung  (Chinese  wood  oil) 
Soya-bean  oil  

227 


SOAP-MAKING    MANUAL 


Physical  and  Chemical  Constants  of  Fixed  Oils  and 
Fats. 

(FROM  LEWKOWITSCH  AND  OTHER  AUTHORITIES.) 


Saponificatton 
value. 

Muumene 
teat. 

Iodine  value. 

Hehner 
value. 

Reichcrt 
value. 

Linseed  oil  

190-195 

104°-111° 

176-190 

Hemp-seed  oil   .... 

190-193 

96°-96° 

148 

Walnut  oil  .  . 

195 

96M010 

144-147 

Poppy-seed  oil  .... 
Sunflower  oil  ... 

195 
193-194 

86°-88° 
72°-75° 

134-141 
120-129 

95.38 
95 

Fir-seed  oil  .  . 

191.3 

98°-99° 

118  9-120 

*    •     • 

Maize  oil  

388-193 

56MJO  5° 

117  125 

89-957 

•    25 

Cotton-seed  oil  .... 
Sesame  oil    .  . 

191-195 
189-193 

68°-77° 
64°-68° 

104-110 
106-109 

96-17 
958 

°035 

Rape-seed  oil  
Black  mustard  oil  .  .  . 
Crotonoil    ...... 
Castor  oil  . 
Apricot-  kernel  oil  .  .  . 

170-178 
174-174.6 
210.3-215 
178-186 
192.2-193.1 

51°-60° 
43°-44° 

'  46°U7°  ' 
42.5°-46° 

95-105 
96M10 
101.7-104 
83.4-85.9 
100-107 

95 
95.05 
89 

'13.5' 
14 

Almond  oil  
Peanut  (arachis)  oil  .  . 
Olive  oil   
Menhaden  oil  - 
Cod-liver  oil   
Seal  oil  

190.5-195.4 
190-197 
191-196 
189.3-192 
182-187 
190-196 

51°-54° 
45°-49° 
41.5e-45.50 
123M280 
102M030 
92° 

93-97 
85-98 
80.6-84.5 
140-170 
154-180 
127-140 

96.2 
95.86 
95.43 

95.3 
942 

*o!s  ' 

1.2 
'022* 

Whale-oil  

188-193 

91°-92° 

110-136 

93.5 

2.04 

1973 

995 

9307 

66 

Dolphin  oil  |  jaw  oil 

200 

32.8 

66.28 

65.92 

Porpoiseoilj^f 
Neat's-foot  oil 

216-218.8 
253.7 
1943 

60° 
'  47°-485°' 

119.4 
49.6 
69.3-70.4 

'  6841.  ' 

23.45 
65.8 

Cotton-seed  stearine 
Palm  oil   

194.6-195.1 
196.3-202 
192.2-193.5 

48° 

88.7-92.8   : 
63-57 
32-41 

96.3 
95.6 
94.69 

1.6 

250-253 

8.5-9.3 

88.6 

3.7 

Myttle  wax 

205  7  211  7 

29 

220-222  4 

4.2-8.5 

90.6 

Lard  ...  
Bone  fat 

195.3-196.6 
1909 

27°-32° 

57-70 
46.3-49.6 

96 

.    ,    . 

Tallow 

195-198 

36-47 

95.6 

0.25 

221  5-227 

26-35 

87.5 

28.78 

Oleomargarine   .  .  . 
Sperm  oil  
Bottle-nose  oil    .      .  . 
Camauba  wax    .      .  . 
Wool-fat 

194-203.7 
132.5-147 
126-134 
80-84 
98  2-102  4 

41°-47° 

65.3-60 
84 
77.4-82 
13.5 
25-28 

95-96 

2.6 
1.3 
14 

83-11 

128 

63 

193 

150-165 

. 

Soya-bean  oil  

190.6-192.9 

59°-61° 

121.3-124 

95.5 

'    *    ' 

228 


*Temperature  Correction  Table  for  Hehner's  Concen- 
trated Bichromate  Solution  for  Glycerine  Analysis 


A 

Temperature* 

f 

Corrected  Volume 
1  c.  c. 

Logarithm 

11°  C 

0  9980ccm 

99918 

12°  " 

0.9986   "' 

99935 

13°  " 

0.9990   " 

99956 

HO- 

0.9995  " 

99978 

IS'" 

1.0000   " 

00000 

16°  " 

.0005  " 

00022 

17°" 

.0010   '' 

00043 

18<>  " 

.0015   " 

00065 

19°  " 

.0020   " 

00087 

20°  " 

.0025   " 

00108 

21o  » 

.0030   " 

00130 

22°  " 

.0035   " 

00152 

18°  V 

.0040   " 

00173 

*Table  of  Important  Fatty  Acids 


Name 

Formula 

Mol. 
Wt. 

Boiling  Point 

Melt- 

£ 

Neutral, 
feation 

value 

Kdfe 

Ordinary 

Pressure 

100  mm 

Pressure 

Butyric  
Caproic.  .  ,  .  . 
Cap^Jic.... 
Capric.  ...  .  . 

C4  H8  02 
C6H)202 
C8H,602 
C,oH2002 
Ci2H24  02 
C|-4  H28  O2 
C,«H3202 
C18H3<J02 
C2oH4o  02 
C22  H4402 
C27  H54  02 
C3o  H6O  02 
C,8H3402 
C22H4202 
C18SS202 
C18H3002 
Gia  H34  O3 

88 
116 
144 
172 
200 
228 
256 
284  ' 
302 
330 
400 
442 
282 
338 
280 
278 
298 

162.3 
199.7 
236—237 
268—270 

I 

199.5—200 
225 
250.5 
268.5 
291 

185.5—286 

16.5 
31.3 
43.6 
53.8 
62 
69.2 
76 
77-78 
78 
90 
14 
33-34 

637.5 
483.6 
389.6 
326.2 
280.5 
246.1 
219.1 
197.5 
185.8 
170.0 
140.25 
126.5 
198.9 
165.9 
200.4 
201.8 
131.5 

Laurie./,  .  '.  . 

Myristic  
Palmitic.  ... 
Stearic  ..,   . 

Arachidic   . 
Behenic  
Cerotic..... 
Melissic..... 
Oleic  
Erucic..,,,  . 
Linolic...... 
Linolenic.'.  .  . 
Ricinoleic.  .  . 

SOAP-MAKING     MANUAL 

"Comparison  of  Thermometer  Scales 

n  Degree  Celsius— f-n  Degree  Reaumur=82-|-f  n  Degree  Fahrenheit 
n  Degree  Reaumur— |-n  Degree  Cebius=82-|~Jn  Degree  Fahrenheit 
n  Degree  Fahrenheit=-f-(n— 82)  Degree  Celsiu8=— (n— 82)  Deg.  R 


c. 

R. 

F. 

C. 

R. 

F. 

C. 

R, 

F. 

C. 

R. 

F. 

—20 

—18 

_^ 

20> 

16 

68 

60 

140 

100 

80 

212 

—19 

—18.2 

—2.2 

21 

16.8 

69.8 

61 

.8 

141.8 

101 

80.8 

213.6 

—18 

—14.4 

—0.4 

22 

17.6 

71.6 

62 

49.6 

143.6 

102 

81.6 

216.6 

—17 

—18.6 

1.4 

23 

18.4 

78.4 

63 

60.4 

145.4 

103 

82.4 

217.4 

—16 

—12.8 

8.2 

24 

19.2 

76.2 

64 

61,2 

147.2 

104 

83.2 

219.2 

—16 

—12 

5 

25 

20 

77 

66 

62 

149 

106 

84 

221 

—14 

—"11  £ 

6.6 

26 

20.8 

78.8 

66 

52.8 

150.8 

106 

84.8 

222.8 

—18 

—  I0i4 

8.6 

27 

21.6 

80.6 

67 

63.6 

162.6 

107 

85.6 

224.6 

—12 
—11 

-1:1 

10.4 
12.2 

28 
29 

22.4 
28.2 

i5:S 

68 
69 

64.4 

65.2 

154.4 
166.2 

108 
109 

86.4 
87.2 

226.4 
228  2 

—10 
—  0 

rl 

14 
16.8 

80 
81 

24 

24. 

86 
87.8 

70 
71 

66 

66.8 

168 
169.8 

110 
111 

Sf.6 

2818 

—  6. 

17.6 

82 

26. 

89.6 

72 

67.6 

161.6 

112 

89.6 

238!  6 

=  6 

19.4 
21.2 

« 

26. 
27. 

91.4 
98.2 

73 
74 

68.4 
69.2 

168.4 
166.2 

118 
114 

90.4 
91.2 

235.4 
237.2 

—  6 

—  4 

28 

86 

28 

08 

76 

167 

116 

92 

239 

—  4 

—  8. 

24.8 

86 

28. 

96  8 

76 

.8 

168.8 

116 

92.8 

240.8 

—  2. 
—  1. 

26.6 
28.4 

87 
88 

29. 
30. 

98!  6 
100.4 

77 

78 

61  .« 
62.4 

170.6 
172.4 

117 
118 

93.6 
94.4 

242.6 
244.4 

—  i 

—  0.8 

80.2 

89 

81. 

102.2 

79 

63.2 

174.  e 

119 

95.2 

246.2 

0 

"32 

40 

82 

104 

80 

64 

176 

120 

96 

248 

1 

.8 

83.8 

41 

82 

105. 

81 

64.8 

177.8 

121 

96.8 

249.8 

2 

J.6 

35.6 

42 

33 

107. 

82 

«8.6 

179.6 

122 

97.6 

262.6 

8 

4 

. 
8.2 

87.4 
39.2 

48 
44 

84.' 
86. 

109. 
111. 

88 
84 

66.4 

67.* 

181.4 
188.2 

123 
124 

98.4 
99.2 

268.4 
266V2 

6 

4 

41 

46 

86 

118 

86 

68 

186 

126 

100 

267 

6 
1 

4.8 
6.6 

42.8 
44.6 

46 
47 

86. 
87. 

114. 
116. 

86 
87 

68.8 
69.6 

51? 

100.8 
101.6 

ISS:f 

S 

6.4 

7.2 

46.4 
48.2 

48 
49 

88. 
89. 

118. 
120. 

88 
89 

70.4 
71.2 

192'.2 

128 
129 

102.4 
108.2 

&i 

10 

8 

60 

60 

40 

122 

90 

72 

194 

180 

104 

266 

11 

8. 

61.8 

61 

40. 

123. 

91 

72.8 

196.8 

181 

104.8 

267.  8 

12 
18 

9. 
10. 

68.6 
55.4 

62 
68 

41. 
42.4 

125. 
127. 

92 
98 

78.6 

74.4 

197.6 
199.4 

132 
188 

iftS 

271  '.4 

14 

11. 

67.8 

64 

48.2 

129. 

94 

76.2 

201.2 

184 

107  A 

278.2 

15 

12 

69 

65 

44 

181 

96 

76 

208 

135 

108 

276 

16 

12. 

60.8 

66 

44.8 

132. 

96 

76.8 

204.8 

136 

108.8 

276.8 

17 

18. 

62.6 

67 

46.6 

134. 

97 

77.6 

206.6 

137 

109.6 

278.6 

IS 

14. 
16.2 

64.4 
66.2 

68 

0$ 

46.4 
47.2 

136. 
138. 

98 
99 

?S:J 

208.4 
210.2 

138 
139 

110.4 
111.2 

280.4 
282.2 

230 


USEFUL     INFORMATION 

'Quantities  of  Alkali  Required  for  Saponif ication  of 
Fats  of  Average  Molecular  Weight  670 

(Cocoanut  Oil,  Palmkernel  Oil) 


Liters  Alkali             Liters  Alkali 
Solution                    Solution 
Kilos  ;        Sp.  Gr.  1.1               Sp.  Gr.  1.2 

Liten  Alkali 
Solution 
Sp.  Gr.  1.3 

Liters  Alkali 
Solution 
Sp,  Gr.  1.355 

Na  OH 

K  O  H  j  Na  OH  j 

KOH 

Na  OH 

KOH 

Na  OH 

KOH 

1000 

1875.83 

1902.99 

844.67; 

930 

35 

510.27 

622 

71' 

409.61 

517 

97 

2000 

3751.66    3805.97    1689.35. 

1860 

70 

1020.54. 

1245.41 

819.21 

1035 

95 

8000 

5627.60 

5708.96   2534.02 

2791 

04!  1530.81 

1868 

12 

1228.82 

1553 

92 

400Q 

7508.33 

7611.94    8378.69, 

8721 

39    2041.01: 

2490 

83 

1638.43    2071 

90 

5000 

9379.16 

9514.93    4223.37 

4651 

74    2551.35 

3113 

54 

2048.04 

2589 

8/ 

6000 

11254  .'99 

11417.91 

5068.04 

5582 

OS    3061.61 

8736 

24 

2457.65 

3107 

.84 

7000 

13130.82,13320.90    5912.71; 

6512 

44    3571.88 

4358.95, 

2867.26    3625 

.82 

8000 

15006.  6615223.  88    6757.38! 

7442 

.78',  4082.15 

4981 

.66 

3276.86;  4143 

.79 

9000 
10000 

16882.4917126.87 

18758.3219029.85 

7602.06! 

8446.73 

8373 
9303 

.It)  4592.42 
.48!  5102.69 

5604 
6227 

.36 
.02 

3886.47    4661 
4096.08    5179 

.77 
.74 

^Quantities  of  Alkali  Required  for  Saponif  ication  of 
Fats  of  Average  Molecular  Weight  860 

(Tallow,  Cottonseed  Oil,  Olive  Oil,  Etc.) 


Liters  Alkali 

Liters  Alkali 

Liters  Alkali 

Liters  Alkali 

KB* 

tfSft, 

Solution 
Sp.  Gr.  1.2 

Solution 
Sp.  Gr.  1.8 

Solution 
Sp  Gr.  1.355 

Na  OH  1  K  0  H 

Na  OH  |  KOH 

Na  OH  |  KOH 

Na  OH  | 

KOH 

1000 

1461.40    1482.561     668.06      724.81 

897.64     485.13 

319.11 

403.54 

2000      2922.81    2965.12!  1316.12    1449.61 

795.07J     970.  2?|     638.23; 

807.08 

3000      4384.211  4447.67 

1974.18    2174.42 

1192.61    1455.40,     957.34 

1210.61 

4000      5845.62    6930.23  "2632.24    2899.22    1590.14    1940.53 

1276.45 

1614.15 

6000      7307.  02|  7412.79    3290.80    3624.03    1987.  68!  2425.67 

1595.57; 

2017.69 

60CO      8768.42    8895  85    3948.35;  4348.84    2385.21,  2910.80 

1914.68. 

2421.23 

7000    10229.8310377.91 

4606.41    6073.64 

2782.75    8395.93 

2233.79 

2824.77 

8000    11691.23  11860.46    5264.4?!  5798.45 

3180.28    3881.06 

2552.90, 

3228.30 

9000    13152.64  13348.02 

6922.53    6523.25 

3577.82    4366.20 

2872.02 

3631.84 

10000    14614.0414825.58 

6580.69    7248.06 

3975.35    4851.33 

3191.13 

4035.38 

I                                  I                                  ! 

—  „  - 



231 


SOAP-MAKING    MANUAL 


DENSITY    AND     STRENGTH     OF    SULPHURIC 
ACID     (SIDERSKY). 


1 

0 

IS 

S*^* 

Equivalent 
(in^cc.) 

1 

CJ 

3 

"3 

Equivalent 
(in  cc.) 

1 

rt 

. 

4>'* 
3§ 

*« 

** 

1 

to 

rt 

*I 

IM 

«4H 

o    . 

<-IH 

(0 

. 

p|C/j 

o'S 

QJ  'o 

W3 

. 

a^ 

2*8 

0 

0 

«+*w 

.•3  rt 

•)H    rt 

g 

U 

s^ 

;S  w 

1 

o, 

O"-' 

«£ 

rt  « 

« 

d 

OV 

rt  JJ 

o 

fc£ 

"SS 

o  a, 

Q 

c/J 

fc£ 

0  0, 

*°  a 

1 

1.007 

1.9 

52.620 

96.930 

62 

.308 

40.2 

1.905 

3.508 

3 

1.014 

2.8 

35.710 

66.450 

64 

.320 

41.6 

1.821 

3.354 

4 

1.022 

3.8 

25.650 

47.230 

66 

.332 

43.0 

1.745 

3.214 

6 

1.029 

4.8 

20.410 

37.582 

69 

.345 

44.4 

1.665 

3.085 

8 

1.037 

5.8 

16.670 

30.690 

71 

.357 

45.5 

1.621 

2.985 

9 

1.045 

6.8 

14.085 

25.938 

74 

.370 

46.9 

1.558 

2.869 

10 

1.052 

7.8 

12.198 

22.460 

77 

.383 

48.3 

1.497 

2.757 

12 

1.062 

8.8 

10.755 

19.803 

80 

.397 

49.8 

1.436 

2.646 

13 

1.067 

9.8 

9.524 

17.540 

82 

.410 

51.2 

1.386 

2.551 

15 

1.075 

10.9 

8.547 

15.740 

85 

.424 

52.6 

1.335 

2.459 

17 

1.083 

11.9 

7.752 

14.278 

88 

.438 

54.0 

1.287 

2.370 

18 

1.091 

13.0 

7.042 

12.969 

91 

.453 

55.4 

1.237 

2.270 

20 

1.100 

14.1 

6.452 

11.882 

94 

.468 

56.9 

1.195 

2.200 

22 

1.108 

15.2 

5.953 

10.962 

97 

.483 

58.3 

1.156 

2.130 

23 

1.116 

16.2 

5.526 

10.177 

100 

.498 

59.6 

1.116 

2.050 

25 

1.125 

17.3 

5.405 

9.954 

103 

.514 

61.0 

1.080 

1.980 

27 

1.134 

18.5 

4.76 

8.770 

106 

.530 

62.5 

1.045 

.930 

29 

1.142 

19.6 

4.465 

8.223 

108 

.540 

64.0 

1.010 

.860 

30 

1.152 

20.8 

4.184 

7.723 

113 

.563 

65.5 

0.975 

.800 

32 

1.162 

22.2 

3.876 

7.138 

116 

1.580 

67.0 

0.950 

.740 

34 

1.171 

23.3 

3.663 

6.745 

120 

1.597 

68.6 

0.917 

.690 

36 

1.180 

24.5 

3.541 

6.521 

123 

1.615 

70.0 

0.888 

.630 

38 

1.190 

25.8 

3.258 

5.999 

127 

1.634 

71.6 

0.855 

.570 

40 

1.200 

27.1 

3.077 

5.666 

130 

1.652 

73.2 

0.845 

.520 

42 

1.210 

28.4 

2.907 

5.353 

134 

1.671 

74.7 

0.800 

.470 

44 

1.220 

29.6 

2.770 

5.102 

138 

1.691 

76.4 

0.774 

.430 

46 

1.231 

31.0 

2.618 

4.865 

142 

1.711 

78.1 

0.749 

.390 

48 

1.241 

32.2 

2.500 

4.604 

146 

1.732 

79.9 

0.722 

.320 

50 

1.252 

33.4 

2.392 

4.406 

151 

1.753 

81.7 

0.705 

.280 

53 

1.263 

34.7 

2.283 

4.205 

155 

1.774 

84.1 

0.672 

.235 

55 

1.274 

36.0 

2.179 

4.012 

160 

1.798 

86.5 

0.639 

.190 

57 

1.285 

37.4 

2.079 

3.829 

164 

1.819 

89.7 

0.609 

.130 

60 

1.297 

38.8 

1.988 

3.661 

168 

1.842 

100.0 

0.544 

1.000 

232 


USEFUL    INFORMATION 

"'Densities  of  Potassium  Carbonate  Solutions 

at  15  C  (Gerlach) 


Sp.  Gr. 

Per  cent 
of  pure 
K2C03 

1 
Sp.Gr. 

Per  cent 
of  pure 
K2C03 

Sp.  Gr. 

Per  cent 
of  pure 
K2C03 

.00914 

1 

1.18265 

19 

1.38279 

37 

.01829 

2 

1.19286 

20 

1.39476 

38 

.02743 

3 

1.20344 

21 

1.40673 

39 

.03658 

4 

1.21402 

22 

1.41870 

40 

.04572 

5 

1.22459 

23 

1.43104 

41 

.05513 

6 

1.23517 

24 

1.44338 

42 

.06454 

7 

1.24575 

26 

1.45573 

43 

.07396 

8 

1.25681 

26 

1.46807 

44 

.08337 

9 

1.26787 

27 

1.48041 

45 

.09278 

10 

1.27893 

28 

1.49314 

46 

.10258 

11 

1.28999 

29 

1.50588 

47 

.11238 

12 

1.30105 

30 

1.61861 

48 

.12219 

13 

.31261 

31 

1.63135 

49 

1.13199 

14 

.32417 

32 

1.64408 

60 

1.14179 

15 

.33573 

33 

1.65728 

51 

1.15200 

16 

.34729 

34      , 

1.67048 

i    62 

1.16222 

17 

.35885 

35 

1.67079 

1    63.024 

1.17243 

18 

.37082 

36 

"Constants  of  Certain  Fatty  Acids  and  Triglycerides 


Triglyccridw 
of 

Mol.  Wt. 

of  Fatty 
Acid 

Mol.  Wt. 
ofTri- 
glycerides 

Per  cent  YieW 

Fatty 
Acid 

Glycerine 

Stearic  Acid 

284 
282 
270 
266 
228 
200 
172 
116 
88 

890 
884 
848 
806 
722 
638 
694 
386 
302 

95.78 
95.70 
95.52 
95.28 
94.47 
94.04 
93.14 
90.16 
87.41 

10,34 

10:41 

10.85 
11.42 
12.74 
14.42 
16.48 
23.83 
30.46 

OleicAcid  
Margaric  Acid 

Palmitic  Acid  ...... 

Myristic  Acid  

Laurie  Acid.. 

Capric  Acid  

Caproic  Acid  . 

Butyric  Add  

SOAP-MAKING     MANUAL 

PERCENTAGES  OF  SOLID  CAUSTIC  SODA  AND  CAUSTIC 
POTASH  IN  CAUSTIC  LYES  ACCORDING  TO  BAUME  SCALE. 
Degrees 
Baume. 

1 

2 

3 

4 

5 

6 

7.  . 


9 

10 
11 
12 
13 
14 
15 
16 
17 
18 
19 
20 
21 
22 
23 
24 
25 


NaOH 

0.61 

0.93 

2.00 

2.71 

3.35 

4.00 

4.556 

5.29 

5.87 

6.55 

7.31 

8.00 

8.68 

9.42 

10.06 

10.97 

11.84 

12.64 

13.55 

14.37 

15.13 

15.91 

16.77 

17.67 

18.58 


KOH 

0.90 

1.70 

2.60 

3.50 

4.50 

5.60 

6.286 

7.40 

8.20 

9.20 

10.10 

10.90 

12.00 

12.90 

13.80 

14.80 

15.70 

16.50 

17.60 

18.60 

19.50 

20.50 

21.40 

22.50 

23.30 


GLYCERINE   CONTENT   OF    MORE 
FATS    USED   IN    SOAP 


Degrees  %  % 

Baume.  NaOH  KOH 

26 19.58  24.20 

27 20.59  25.10 

28 21.42  26.10 

29 22.64  27.00 

30 23.67  28.00 

31 24.81  28.90 

32 25.80  29.80 

33 26.83  30.70 

34 27.80  31.80 

35 28.83  32.70 

36 29.93  33.70 

37 31.22  34.90 

38 32.47  35.90 

39 33.69  36.90 

40 34.96  37.80 

41 36.25  38.90 

42 37.53  39.90 

43 38.80  40.90 

44 39.99  42.10 

45 41.41  43.40 

46 42.83  44.60 

47 44.38  45.80 

48 46.15  47.10 

49 47.58  48.25 

50 49.02  49.40 

COMMON   OILS  AND 
MAKING. 

&L  5. 


Beef  Tallow 10.7 

Bone  Grease 10.5 

Castor   Oil 9.8 

Cocoanut   Oil 13.9 

Cocoanut  Oil  Off 

Corn  Oil 10.4 

Cottonseed  Oil 10.6 

Hog  Grease 10.6 

Horse  Grease 10.6 

Olive   Oil 10.3 

Olive  Foots 

Palm   Oil 11.0 

Palmkernel    Oil 13.3 

Peanut  Oil 10.4 

Soya  Bean  Oil 1C.4 

Train  Oil 10.0 

Vegetable  Tallow....  10.9 


5 

20—50 

0.5—10 

3—5 

15—40 
1—10 
Trace 

0.5—1 
1—3 
2—25 

30—60 

10—50 
4—8 
5—20 
2 

2—20 
1—3 

234 


10.2 

5.2—  8.4 
8.8—  9.8 

13.2—13.5 
8.3—11.8 
9.3—10.3 

10.6 

10.5—10.6 

10.5—10.6 
7.7—10.2 

4—7 
5.5—10 

12.2—12.8 

8.3—  9.9 
10.2 

8—  9.8 
10.5—10.8 


12.75 

6.5 
11.0 
16.5 
10.37 
11.62 
13.25 
13.12 
13.12 

9.62 
5 

6.87 
15.25 
10.37 
12.75 
10.0 
13.12 


10.5 

12.45 

16.9 

14.75 

12.9 

13.25 
13.25 
12.75 
8.75 
12.5 
16 
12.37 

12.25 
13.5 


USEFUL     INFORMATION 

Table  of  Specific  Gravities  of  Pure  Commercial 

Glycerine  with  Corresponding  Percentage  of 

Water.    Temperature  15  C. 


Sp.  Gr. 

Sp.  Gr. 

.262 

0     Water 

1.160 

38% 

Water 

.261 

1%       "  ' 

1.157 

39" 

" 

.258 

2" 

1.155 

40" 

•• 

.255 

3" 

1.152 

41" 

" 

.2515 

4" 

1.149 

42" 

•• 

.250 

6  "        " 

1.1464 

43" 

" 

.2467 

6  " 

1.1437 

44" 

" 

.2450 

7" 

1.141 

45" 

•' 

.243 

8" 

1.1377 

46" 

•• 

.241 

9" 

1.1353 

47" 

»«- 

.237 

10  " 

1.1326 

48" 

•• 

.235 

11  " 

1.1304 

49" 

•• 

.2324 

12  " 

1.127 

60" 

•• 

.229 

13  " 

1.125 

61" 

•' 

.2265 

14  "        " 

1.1224 

52" 

»• 

.2245 

15  " 

1.1204 

53" 

•• 

1.2225 

16  " 

1.117 

54" 

M 

1.2185 

17  " 

1.114 

65" 

" 

1.2174 

18  " 

1.112 

66" 

" 

.2142 

19  " 

1.109 

67" 

" 

.211 

20  " 

1.106 

68" 

" 

.207 

21  " 

.103 

69*' 

" 

.203 

22  " 

.1006 

60" 

" 

.2004 

23  " 

.088 

65" 

»» 

.198 

24  " 

.075 

70" 

1* 

.195 

25  " 

.0623 

76" 

" 

.1923 

26  " 

.049 

80" 

n 

.189 

27  " 

.0365 

85" 

•• 

.188 

28  " 

.0243 

90" 

it 

.1846 

29" 

.0218 

91  " 

11 

.182 

30  " 

.0192 

92  " 

n 

.179 

31  " 

.0168 

93" 

" 

.176 

32  " 

.0147 

94" 

•• 

.1734 

33  " 

.0125 

95" 

" 

.171 

34  " 

.01 

96" 

" 

.168 

55  " 

.0074 

97" 

" 

.165 

86  " 

.0053 

98" 

" 

.163 

87  " 

.0026 

99" 

it 

235 


SOAP-MAKING    MANUAL 


*Table  of  Percentage,  Specific  Gravity  and  Beaume 
Degree  of  Pure  Glycerine  Solutions 


Per  cent 
Water 

Sp.  Gr. 

Champion 
and  Pellet 

Degree 
Beaume 

Oerthelot) 

Per  cent 
Water 

Sp.Gr. 

Champion 
and  Pellet 

Degree 

Beaume 
(Berthelot) 

0 
.6 

.2640 
.2625 

31.2 
31.0 

11.0. 
11.6 

1.2350 
1.2335 

n.4 

.0 

.2612 

30.9 

12.0 

1.2322 

28.3 

.6 

.2600 

30.8 

12.5 

1.2307 

28.2 

.0 

.2585 

30.7 

13.0 

1.2296 

28.0 

.6 

.2575 

30.6 

13.5 

1.2280 

27.8 

.0 
.5 

.2560 
.2545 

30.4 
30.3 

14.0 
14.6 

1.2270 
1.2255 

27.7 
27.6 

.0 

.2532 

30.2 

15.0 

1.2242 

27.4 

.6 

.2520 

30.1 

15.5 

1.2230 

27.3 

.0 

.2505 

30.0 

16.0 

1.2217 

27.2 

.6 

.2490 

29.9 

16.5 

1.2202. 

27.0 

.0 
.5 
.0 

.2480 
.2465 
.2455 

29.8 
29.7 
29.6 

17.0 
17.5 
18.0 

1.2190 
1.2177 
1.2165 

26.9 
26.8 
26.7 

.6 

.2440 

29.5 

18.5 

1.2150 

26.5 

.0 
.5 

.2427 
.2412 

29.3 
29.2 

19.0 
19.5 

1.2137 
1.2125 

26.4 
26.3 

.0 

.2400 

29.0 

20.0 

1.2112 

26.2 

.6 

.2390 

28.9 

20.5 

1.2100 

26.0 

10.0 

.2375 

28.8 

21.0 

1.2085 

25.0 

10.6  ' 
«*:  •       '= 

.2362 

28.7 

1 

236 


USEFUL     INFORMATION 


Table  of  Specific  Gravities  of  Pure  Glycerine  Solu- 
tions with  Corresponding  Beaume  Degree 
and  Percent  Water 


Percent 
Water 

Sp.  Gr. 

Degree 
Beaume 

Percent 
Water 

Sp.  Gr. 

Degree 
Beaume 

0.0 

1.2640 

31.2 

1.0 

.2612    ' 

30.9 

0.5 

1.2625 

31.0 

1.5 

.2600 

30.8 

2.0 

1.2585 

30.7 

12.0 

.2322 

28.3 

2.5 

1.2575 

30.6 

12.5 

.2307 

28.2 

3.0 

1.2560 

80.4 

13,0 

.2295 

28.0 

3.6 

1.2545 

30.3 

13.6 

.2280 

27.8 

4.0 

1.2532 

30.2 

14.0 

.2270 

27.7 

4.5 

1.2520 

30.1 

14.5 

.2255 

27.6 

5.0 

1.2505 

30.0 

1£.0 

.2242 

27. 

5.5 

1.2490 

29.9 

15.5 

.2230 

27. 

6. 

1.2480 

29.8 

16.0 

.2217 

27. 

6. 

1.2466 

29.7 

16.6 

.2202 

27. 

7. 

1.2455 

29.6 

17.0 

.2190 

26. 

7. 

1.2440 

29.6 

17.6 

.2177 

26. 

8. 

1.2427 

29.3 

18.0 

.2165 

26.7 

8. 

1.2412 

29.2 

18.6 

.2160 

26.6 

9. 

1.2400 

29.0 

19.0 

.2137 

26.4 

9. 

1.2390 

28.9 

19.6 

.2126 

26.8 

10. 

1.2376 

28.8 

20.0 

.2112 

26.2 

10. 

1.2362 

28.7 

20.6 

.2100 

26.0 

11. 

1.2350 

28.6 

21.0 

.2086 

25.9 

11. 

1.2886 

28.4 

f 

i 

237 


INDEX 


Acetin  process  for  the  deter- 
mination of  glycerol,  155. 

Acid,    Clupanodonic,    20. 

Acid,  Hydrochloric,   111. 

Acid,   Laurie,  2. 

Acid,    Myristic,    2. 

Acid,  Napthenic,  24. 

Acid,    Oleic,    15,    19. 

Acid,   Palmitic,  2. 

Acid,    Pinic,    22. 

Acid,  Resin,  144. 

Acid,  Stearic,  15,  19. 

Acid,   Sulfuric,  112. 

Acid,   Sylvic,  22. 

Acid  saponification,  120. 

Air  bleaching  of  palm  oil,   12. 

Albuminous  matter,  Removal 
from  tallow,  6. 

Alcohol,   Denatured,   82. 

Alcoholic  method  for  free  alkali 
in  soap,  139. 

Alkali  Blue  6  B,  indicator,  129. 

Alkali,  Total,  determination  of  in 
soap,  147. 

Alkalis,  25. 

Alkalis  used  in  soap  making, 
Testing  of,  134. 

Amalgamator,  33. 

Analysis,  Glycerine,  Interna- 
tional, 150. 

Analysis,  Soap,  137. 

Analysis,  Standard  methods  for 
fats  and  oils,  165-196.  ' 

Aqueous  saponification,  121. 

Arachis  oil,  79. 

Autoclave  saponification,    118. 

Automobile  soaps,  41. 

B 

Barrels,  sampling,   168. 

Baume  scale,  25. 

Bayberry  wax,  Use  in  shaving 
soap,  89. 

Bichromate  Process  for  glycerol 
determination,  160. 

Bleaching,  Fullers'  earth  process 
for  tallow,  4. 

Bleaching  palm  oil  by  bichro- 
mate method,  9. 


Bleaching  palm  oil  by  air,  12. 

Bosshard  &  Huggenberg  method 
for  determination  of  free  al- 
kali, 140. 

Bunching  of  soap,  52. 

C 

Candelite,  96. 

Candle  tar,  125. 

Carbolic  soap,  77. 

Carbon  Dioxide,  Formation  of  in 

carbonate  saponification,  45. 
Cai  Donate,    potassium,    29. 
Carbonate,  saponification,   35,  45. 
Carbonate,  sodium,  28. 
Castile  soap,  79. 
Castor   oil    ferment,    121. 
Castor  oil,  Use  of  in  transparent, 

soaps,  83. 
Caustic  potash,  26. 
Caustic  potash,  Electrolytic,  27. 
Caustic  soda,  26. 
Changes  in  soap-making,  36. 
Chemist,  Importance  of,  127. 
Chipper,  Soap,  32. 
Chip  soap,  54. 

Chip    soap,    Cold    made,    55. 
Chip  soap,  Unfilled,  56. 
Chrome  bleaching  of  palm  oil,  9. 
Cloud     test     for     oil,      Standard 

method,    182-183. 
Clupanodonic  acid,  20. 
Cocoanut  oil,  6. 
Cold  cream  soap,  78. 
Cold  made  chip  soaps,  55. 
Cold  made  toilet  soaps,  72. 
Cold  made  transparent  soap?,  84. 
Cold  process,  35,  43. 
Colophony,  22. 
Coloring  soap,  75. 
Copra,  7. 
Corn  oil,  14. 
Corrosive    sublimate,    78. 
Cotton    goods,    Soaps    used    for, 

103. 

Cottonseed  oil,  14. 
Cream,  Shaving,  90. 
Crude   glycerine,   113. 
Crutcher,  32. 
Curd  soap,  71. 
Cutting  table,  32. 


239 


SOAP-MAKING  MANUAL 


Determination  of  free  fatty  acid, 

128.   . 
Determination    of    unsaponifiable 

matter,   132. 

Distillation  of  fatty  acids,  125. 
Drying  machine,  32. 

E 

Enzymes,  17. 
Eschweger  soap,  81. 
Examination    of    fats    and    oils, 
128. 

F 

Fahrion's  method  for  moisture, 
138. 

Fats  and  oils,  Examination  of, 
128. 

Fats  and  oils  used  in  soap  manu- 
facture, 3. 

Fatty  acids,  14. 

Fatty  acids,  Distillation  of,  125. 

Ferments,  Splitting  fats  with, 
121. 

Fillers  for  laundry  soaps,  53. 

Fillers  for  soap  powders,   58. 

Finishing  change,  36. 

Fish  oils,  20. 

Floating  soap,  62. 

Formaldehyde  soap,  78. 

Frames,  31. 

Free  alkali  in  soap,  Determina- 
tion of,  139. 

Free  fatty  acid,  Determination 
of,  128. 

Free  fatty  acids,  Extraction  from 
tallow,  6. 

Free  fatty  acid,  Standard  method 
of  dilu.,  174  Note  on  method, 
188-189. 

Full  boiled  soaps,  35. 

Fullers'  earth  bleaching  of  tal- 
low, 4. 

G 

Glycerides,  2. 

Glycerine,  2. 

Glycerine  analysis,   150. 

Glycerine  change,  36. 

Glycerine,  Crude,  113. 

Glycerine  in  spent  lyes,  Recov- 
ery of,  106. 

Glycerine  in  soap,  Determination 
of,  149. 

Glycerine,   Sampling  crude,   162. 


Glycerine  soaps,   83. 

Glycerol  content,  Ways  of  cal- 
culating actual,  159. 

Glycerol  determination,  Acetin 
process,  155. 

Glycerol  determination,  Bichro- 
mate process  for,  160. 

Graining  soap,  30. 

Grease,    21. 

Grease,  Bleaching,  21. 

Grinding  soap,   34. 

H 

Hand  Paste,  93. 
Hard  water,  29. 
Hardened  oils  in  toilet  soap,  Use 

of,  96. 

Hydrocarbon  oils,  2. 
Hydrogenating  oils,    19. 
Hydrolysis    of   fats   and   oils,    17. 
Hydrolytic    dissociation    of    soap, 

1. 
Hydrometers,  25. 


Indicators,  Action,   135-6. 

Insoluble  impurities  in  fatty  oils, 
Determination  of  (standard 
method)  172.  Note  on  method 
187. 

Insoluble  matter  in  soap,  deter- 
mination of,  143. 

International  committee  on  gly- 
cerine analysis,  150. 

Iodine    manufacturing    oil,     191. 

Iodine  member  Wijs  method, 
Standard,  177-181.  Note  on 
method,  191. 

Iodine  soap,   7.8. 

J 
Joslin,  ref.,   113. 

K 

"Killing"  change,  36. 
Koettstorfer    number     (Standard 

method),    181-182. 
Kontakt  reagent,   117. 
Krebitz  Process,  123. 
Krutolin,  96. 

L 
Leiste     &     Stiepel     method     for 

rosin  in  soap,   146. 
Liebermann,       Storch      reaction, 
144. 


240 


INDEX 


Light    powders,    60. 

Laundry  soap,  48. 

LeBlanc  Process,  28. 

Lewkowitsch,  ref.,   17,   146. 

Lime  saponification,    118. 

Lime,  Use  in  Krebitz  Process, 
123. 

Lime,  Use  in  treatment  of  gly- 
cerine water,  116. 

Liquid  medicinal  soaps,  79. 

Liquid  soaps,  94. 

Lyes,    Spent,    37. 

M 

Magnesia,      Use      in      autoclave 

saponification,  120. 
Manganese    sulfate,    Use    of    as 

catalyzer  in  fermentative  cleav- 
age of  fats,  122. 
Marine  soaps,  39. 
Medicinal   soaps,   76. 
Medicinal  soaps,  Less  important, 

78. 
Medicinal       soaps,       Therapeutic 

value  of,  76. 
Melting     point     of     fat     or     oil, 

Standard  method,  193. 
Mercury   soaps,  78. 
Metallic  soaps,   1. 
Methyl   orange,   indicator,    136. 
Meyerheim,  ref.,  21. 
Mill   soap.   32. 
Moisture  in  soap,  Determination 

of,   138,    130. 
Moisture  and   volatile  matter   in 

fats        and        oils.        Standard 

method  for  detm.  of,  170.  Note 

on     method,     184-185. 
Mottle  in  soap,   81. 
Mug  shaving   soap,   90. 

N 

Naphtha,  Incorporation  in  soap, 
49. 

Naphthenic  acids,  24. 

Nigre,   36. 

Normal  acids,  Equivalent  in  al- 
kalis, 136. 

O 

Oils  and  fats,   1. 
Oils     and     fats,     Chemical     con- 
stants, 18. 

Oils  and  fats,  Distinction,   1. 
Oils  and  fats,  Preserving,  18. 


Oils  and  fat.  Nature  of  used  in 

soap  manufacture,  2. 
Oils  and  fats,  Rancidity  of,  16. 
Oil  hardening,   19. 
Oleic  acid,    15,    19. 
Olein,   2,   19. 
Olive  oil,    14. 
Olive   oil    foots,    14. 
Organoleptic  methods,   127. 


Palmatin,  2. 

Palm   kernel    oil,    8. 

Palmitic    acid,    2. 

Palm  oil,  8. 

Palm   oil,   air  bleaching,    12. 

Palm  oil,  Chrome  bleaching  of, 
9. 

Palm  oil  soap,  66. 

Pearl   ash,   29. 

Perfuming  and  coloring  toilet 
soaps,  73. 

Peroxide  soap,  78. 

Petroff  reagent,   117. 

Pfeilring  reagent,   117. 

Phenol,  77. 

Phenolphthalein,   indicator,   38. 

Phenolphthalein,  Using  as  indi- 
cator, 51. 

Phenols,  Soaps  containing,  77. 

Pinic  acid,  22. 

Plodder,  33. 

Potash   from   wood  ash,   27. 

Potassium  carbonate,   29. 

Powders,   Light,  60. 

Powders,    Scouring,    61. 

Powders,    Shaving,    90. 

Powders,   Soap,    56. 

Precipitation  test  for  treated 
spent  lyes,  110. 

Prevention  of  rancidity,   18. 

Pumice  or  sand  soaps,  93. 

Purple   shade    in    soap,    75. 


Rancidity  of  oils  and  fats,  16. 
Rancidity,    Prevention,     18. 
Recovery  of  glycerine  from  spent 

lye,   106. 
Red  oil,  15. 

Red   oil,    Saponified,    15. 
Resin    acids,    Total     fatty    and, 

Determination  of  in  soap,  144. 
Ribot,  ref.,  20. 
Rosin,  22. 


241 


SOAP-MAKING  MANUAL 


Rosin,  Determination  of  in  soap, 

144. 

Rosin    saponification,    23. 
Run  and  glued  up  soaps,  69. 
Run   soaps,   39. 


Sal  soda,  29. 

Salt,  30. 

Salting  out,  30. 

Salt    "pickle,"    37. 

Sampling  crude  glycerine,   162. 

Sampling  for  standard  method, 
166.  Note  on,  184. 

Sampling  oils  and  fat's,   128. 

Sampling  soap,   137. 

Saponification   by    ferments,    121. 

Saponification,    Acid,    120. 

Saponification,  Aqueous,  121. 

Saponification,   Autoclave,    118. 

Saponification,  Carbonate,  45. 

Saponification   defined,    2,    105. 

Saponification,   Lime,    118. 

Saponification    number,    181-182. 

Saponification,  Rosin,  23. 

Saponification,  Various  methods, 
105. 

Scouring  and  fulling  soaps  for 
wool,  98. 

Scouring  powders,  61. 

Scouring  soap,  61. 

Semi-boiled  laundry  soaps,  49. 

Semi-boiled  process,  44. 

Shaving  cream,  90. 

Shaving  powder,  90. 

Shaving  soaps,  87. 

Silica  and  silicates,  Determina- 
tion of  in  soap,  148. 

Silk  dyeing,  102. 

Silk  industry,  Soaps  used  in, 
101. 

Slabber,   32. 

Smith  method  for  moisture  in 
soap,  138. 

Soap  analysis,  137. 

Soap,  Automobile,  41. 

Soap,  Carbolic,  77. 

Soap,  Castile,  79. 

Soap,  Chip,  '54. 

Scan,  Chip,  cold  made,  55. 

Soap,  Chip,  unfilled,  56. 

Soap,  Cold  cream,  78. 

Soap,  Coloring,   75. 

Soap    containing   phenols,    77. 

Soap,  Curd,  71. 

Soap,  Defined,  1. 


Soap,      Determination      insoluble 

matter,   143. 
Soap,    Determining    glycerine    in, 

149. 

Soap,  Eschweger,  81. 
Soap,  Floating,  62. 
Soap,  Formaldehyde,  78. 
Soap     for     wool,     Scouring     and 

fulling,  98. 
Soap,  Full  boiled,  35. 
Soap,  Iodine,  78. 
Soap  kettle,  31. 
Soap,  Laundry,   48. 
Soap,  Liquid,  94. 
Soap  lye  crude  glycerine,   113. 
Soap,  Marine,  39. 
Soap,  Medicinal,  76. 
Soap,    Medicinal,    less    important, 

78. 

Soap,  Mercury,  78. 
Soap,  Metallic,   1. 
Soap,  Peroxide,   78. 
Soap   powders,   56. 
Soap,  Pumice  or  sand,  93. 
Soap,   Rosin   settled,   50. 
Soap,   Run   and  glued  up,   69. 
Soap,    Scouring,    61. 
Soap,    Semi-boiled    laundry,    49. 
Soap,   Shaving,  87. 
Soap,   Sulphur,  77. 
Soap,  Tannin,  78. 
Soap,  Tar,  77. 

Soap,  Test  for  color  of,   133. 
Soap,  Textile,  98. 
Soap,  Toilet,  65. 
Soap,  Toilet  cheaper,  68. 
Soap,  Toilet,  cold  made,  72. 
Soap,   Toilet  perfuming  and  col 

oring,   73. 

Soap,   Transparent,   82. 
Soap,    Transparent,    cold    made. 

84. 

Soap  used  for  cotton  goods,   103. 
Soap   used    in    the    silk    industry. 

101. 

Soap,  Witch  hazel,   78. 
Soap,    Wool    thrower's,    100. 
Soap,  Worsted  finishing,  101. 
Soda  ash,  28. 
Sodium   carbonate,   28. 
Sodium     perborate,     Use     of     in 

soap   powders,    57. 
Soft  soaps,  40. 
Sojuble   mineral   matter   detm.   of 

in  fats  and  oils,  173.     Note  on 

method,    187-188. 


242 


INDEX 


Solvay  process,  28. 

Soya  bean  oil,  14. 

Spent  lye,  Recovery  of  glycerine 
from,   106. 

Spent  lyes,  37. 

Spent    lyes,     Treatment     of    for 
glycerine  recovery,    107. 

Splitting  fats  with  ferments,  121. 

Standard  methods  of  analysis  for 
fats  and  oils,    165-196. 

Starch    and   gelatine,    Determina 
tion  in  soap,   143. 

Stearic  acid,   15,  19. 

Stearin,    2,    19. 

Strengthening  change,  36. 

Strengthening  lyes,  38. 

Strunz  crutcher,  63. 

Sugar  in  soap,  Determination  of, 
150. 

Sugar,   Use  in  transparent  soap, 
83. 

Sulfate    of    alumina,    Use    of    in 
spent  lyes,   108. 

Sulphonated  oils.   104. 

Sulphur  soaps,  77. 

Sweating  of  soap,  62. 

Sweet  water,  119. 

Sylvic    acid,    22. 
T 

Talgol,  96. 

Tallow,  4. 

Tallow,    Fullers'    earth    bleaching 
of,  4. 

Tallow,    Improving   color    by    ex- 
traction of  free  fatty  acid,  6. 

Tannin  soap,  78. 

Tar  soap,  77. 

Test  for  color  of  soap,  133. 

Testing   of   alkalis   used    m    soap 
making,    134. 

Textile  soaps,  98. 

Titer,  130. 

Tank   cars,    Sampling,    166. 

Tierces,    Sampling,    168. 

Titer,    Standard   method,    175. 

Titer,  Note  on,   189. 

Tingoil,    Note    one    iodine,    num- 
ber of,    189 

Toilet  soap,  65. 

Toilet  soaps,  Cheaper,  68. 

Toilet  soap,  Use  of  hardened  oils 
in,  96. 


Total  alkali,  Determination  of  in 
soap,  147. 

Total  fatty  and  resin  acids,  De- 
termination of  in  soap,  144. 

Train  oils,  20. 

Transparent  soap,  82. 

Transparent  soap,  Cold  made, 
84. 

Troweling  soap,  52. 

Tsujimoto,  ref.,  20. 

Tubes    for   transparent   soap,    85 

Turkey  red  oil,  104. 

Twaddle  scale,  25. 

Twitchell  method  for  rosin,   145 

Twitchell  process,  113. 

Twitchell  process,  Advantages. 
113. 

U 

Unsaponifiable  matter,  Determi- 
nation of  in  oils  and  fats,  132. 

Unsaponifiable  matter,  Determi- 
nation of  in  soap,  148. 

Unsaponifiable  matter,  determ- 
ination of  by  standard  method, 
176. 


Vacuum  Oven,    Standard,    176. 
Vegetable  oils,  6. 

W 

Water,  29. 
Water,    Hard,   29. 
Witch  hazel  soap,  78. 
Wool  thrower's  soap,   100. 
Worsted  finishing  soaps,  101. 


Zinc   oxide,   Use  of  in  autoclave 

saponification,   120. 
Zinc  oxide,  Use  of  in  soap,  33 


243 


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Scott,  Wilfred  W.  (Editor).  Standard  Methods  of 
Chemical  Analysis.  A  manual  of  analytical  methods 
and  general  reference  for  the  analytical  chemist  and 
for  the  advanced  student.  Second  Edition,  revised, 
with  additional  tables.  142  illustrations,  3  color  plates. 
7x9*4.  Cloth.  900  pp.  N.  Y.,  1917.  $7.50 

Simmons,  W.  H.     Fats,  Waxes  and  Essential  Oils. 

In  Press. 
Simmons,  William  H.   Soap.    Its  composition,  manufac- 

ture and  properties.    11  illustrations.    4^x7^4-    Cloth. 

133  pp.     London,  1916.  $1.00 

Simmons,  W.  H.,  and  Appleton,  H.  A.  The  Handbook 
of  Soap  Manufacture.  27  illustrations.  6x9.  Cloth. 
166  pp.  London,  1908.  $4.00 

Van  Nostrand's  Chemical  Annual.  Edited  by  John  C. 
Olsen.  A  handbook  of  useful  data  for  analytical 
manufacturing  and  investigating  chemists  and  chemi- 
cal students.  Fourth  Issue,  enlarged.  5x7^2.  Flexi- 
ble fabrikoid.  785  pp.  New  York,  1918.  $3.00 

Watt,  A.  Art  of  Soapmaking.  A  practical  handbook  of 
the  manufacture  of  hard  and  soft  soaps,  toilet  soaps, 
etc.  Seventh  Edition,  revised  and  enlarged.  43  illus- 
trations. 5^x7^-  Cloth.  323  pp.  London,  1918. 

$4.00 

Wright,  C.  R.  A.  Animal  and  Vegetable  Fixed  Oils, 
Fats,  Butters,  and  Waxes:  Their  Preparation  and 
Properties,  and  the  Manufacture  Therefrom  of  Can- 
dles, Soaps,  and  Other  Products.  Third  Edition,  re- 
vised and  greatly  enlarged  by  C.  Ainsworth  Mitchell. 
185  illustrations,  3  plates.  6x9.  Cloth.  953  pp.  Lon- 
don, 1921.  $16.50 


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